The Patent Cooperation Treaty (in initial "PCT") was concluded in 1970 and became effective in 1978. China joined PCT and it became effective in China on January 1, 1994. The Chinese Patent Office also becomes a PCT International Receiving Office, International Search Authority as well as International Preliminary Examination Authority.

A PCT application has two phases: PCT International Phase and PCT National Phase.

1. International Phase: 

(1) receiving patent application and undertake preliminary examination; 

 (2) International Search;

 (3) International Preliminary Examination

2. National Phase: relevant PCT member states exam and decide whether the PCT application can be allowed to become a patent in its country

Qualification of PCT Applicant:

The Treaty stipulates that citizens or residents of the member states have the right to file International applications. Accordingly, Chinese citizens (including entities and individuals, no matter whether its residential address or business office address is inside or outside China) or residents (no matter whether his/her nationality is Chinese) can file the International applications.

The advantages in filing PCT application:

1. one application, in one language (Chinese), filed to one receiving office (the Chinese Patent Office) can obtain the same filing date in each designated countries;

2. with minimum cost, can postpone the national phase entry to the 30th month from the priority date, or 32nd month in some countries, enables the applicant to be in a better situation to collect the fees for national phase;

3. before entering the national phase, can evaluate the economic values of the invention and the possibility of approval to be a patent; having more time to prepare a high quality translation for the examination purpose of each national Patent Office;

4. several chances in the international phase to amend the specification, the amendments made in the international phase can be effective in all designated countries.

Main Procedures in the PCT International Phase:

I. Receiving and conduct formality examination to the patent application

Once the PCT international application is filed by the applicant, the application is deemed filed in all the member states.

The Chinese Patent Office as the PCT receiving office, when deeming that the application documents and procedures are complete, will give the international filing date. International filing date means that from this date, the PCT application in each member state has the effectiveness as a normal domestic application; this filing date is also the actual filing date of the national phase application.

PCT receiving office will conduct formality examination to the application documents, if they pass the examination, they will be sent to WIPO PCT International Bureau as well as International Search Authority respectively.

II. International Search

After filing of a PCT international application, The Chinese Patent Office as one of the International Search Authority will conduct a search for the PCT application within a stipulated time period, and make an International Search Report as well as Written Opinions. The International Search Report as well as written opinions will be sent to the applicant of the PCT application and the PCT International Bureau of WIPO.

Upon expiration of 18 months from the PCT international filing date (or priority date), the PCT International Bureau will publish the PCT international application as well as the search report made by the International Search Authority, and send a copy of the application as well as the search report to each member state patent office. The international publication will not publish the written opinions, however.

III. International Preliminary Examination

The "Patent Cooperation Treaty" stipulates that International Preliminary Examination is not compulsory, to most of the member states, it is neither a pre-condition to enter the national phase in 30 months.

The purpose of the International Preliminary Examination is to provide initial opinions with respect to the novelty, inventiveness and industrial practicability of the invention. The examination opinions are not restriction to each member state. However, the standard regulated by PCT is the current and common standard internationally, and the Examination opinions are made by one of the few International Preliminary Examination Authorities based on the International Search, they are rather reliable.

The Chinese Patent Office as International Preliminary Examination Authority, after the international preliminary examination, will send the examination report to PCT International Bureau and the International Bureau will forward it to the applicant, with a copy to each member state.