can u advise what type of visa should i apply?

Then you should apply for a M type. Except the invitation letter from Chinese company or your partner, you should ask them to get the invitation letter issued by duly authorized Chinese unit. It is usually issued by local foreign affairs office. Besides, you have to provide the introduction letter from your company, which includes your position, purpose of visiting PRC, where to stay and how long you stay. Your company's business license copy version is needed. Also you have to provide a bank account that has at least 4 million Naires. If you went to PRC before, bank account isn't required.