Can I refund the deposit without a deposit slip?

Legal analysis: it can be returned. The deposit paid for renting a house belongs to pledge. Although there is no deposit slip, the landlord should refund the deposit as long as the tenant has not breached the contract. When paying the deposit, the landlord gives the receipt in duplicate, and the landlord keeps one for himself. So as long as you write a written evidence to explain to the landlord that there is no breach of contract and the deposit slip is lost, the landlord should return it.

Legal basis: Civil Code of People's Republic of China (PRC).

Article 425 Where the debtor or a third party transfers his movable property to the creditor to guarantee the performance of the debt, and the debtor fails to perform the due debt or the creditor has the right to be paid in priority for the movable property. The debtor or the third party specified in the preceding paragraph is the pledger, the creditor is the pledgee, and the delivered movable property is the pledged property.

Article 436 Where the debtor performs the debt or the pledger pays off the secured creditor's rights in advance, the pledgee shall return the pledged property. According to the agreement of the parties, if the debtor fails to perform the due debts or realize the pledge, the pledgee may agree with the pledgor to discount or give priority to the payment with the proceeds from auction or sale of the pledged property. Where the pledged property is discounted or sold, it shall refer to the market price.