It depends on the HS code classified for the relevant product. Once the HS code is identified, the relevant custom duty rate can be found on the effective Customs Import and Export Tariff of the People’s Republic of China (http://app.gjzwfw.gov.cn/jmopen/webapp/html5/jckspslPC/index.html). Please keep in mind that, HS codes in China might vary from those used for other countries, as only the first six digits are universally equal; the competent Chinese customs will have the final say on the HS classification (more information can be found in the dedicated FAQ ‘Can I use the same HS code that I use to export in other countries’ in the section ‘Exporting to China’).
It is also noteworthy that every year in December, the Chinese customs and State Council publish annual plans of temporary duty rates for certain goods. The latest plan for 2022 is available at: http://www.gov.cn/zhengce/zhengceku/2021-12/15/content_5660939.htm.