You need to apply for a F (business) visa to China. The requirements are:
1. Your passport valid for at least 6 months with 2 black visa pages.
2. An invitation letter from a unit or company in China which you are going to do business.
3. A passport photo.
4. The application of China visa which you can find on the top of this page.
5. Your residency permit in Spain.
You'd better prepare all these with their copies, and you may asked for other documents by the consular if necessary.