You may need a visa for Mainland China if you have a Vietnamese passport
Visa options for Mainland China (2)
You don't need a visa. You can travel to your destination for a limited stay. Be sure to check other entry requirements and how long you can stay for.
Visitor visa
Travelers need a visa to visit China for Business or Tourism. A paper or embassy visa is the only visa available for travelers visiting China. The visa is typically a stamp or sticker added to the passport. Travelers must obtain this visa from a local embassy, consulate or visa center before traveling. Travelers with valid visas issued before March 28th, 2020, may use them to enter China.
This is not offered by sherpa°.
Apply on the government site.