After passing through the Health Check, you come to the border control area (equivalent to the immigration control in the West) where you show the officer your passport and the Entry Registration Card. Your passport should be valid with a visa to China. 

A tourist visa is necessary and easy to apply for. You can apply for one at the Chinese embassies or consulates in your own country. Without a valid visa, you will find it difficult to enter the country. 

China does not normally issue at-the-border-visas, so you risk being sent back.