Abroad:

1. The European Patent Office patent search website

is a completely free patent document database.

2. The United States Patent and Trademark Office

Contains all patent documents published by the United States Patent Office since 1790.

3. Japan Patent Office Patented Electronic Library

Domestic

State Intellectual Property Office Patent Information Retrieval System

Included since 1985 For all invention patents, utility patents and design patent searches, you can download patent specifications within 100 pages, making it the most authoritative patent search system in the country.