Is it illegal for the landlord to lock the door when he owes rent during the epidemic?

Illegal. The Civil Code of People's Republic of China (PRC) stipulates that if the lessee fails to pay the rent, the landlord needs to make a reminder first. If the tenant fails to pay the rent after being urged, the landlord has the right to ask for the termination of the contract. But before the lease contract is terminated, the lessee still has the right to use the house, and the landlord has no right to lock the door.