I work as a temporary worker in the bank 15, and now the company wants me to sign a contract with the property management company. Is this legal? should have

This is illegal. If you sign a contract with the property management company, it means that you are a temporary employee sent by the property management company to the bank, not a formal employee of the bank, so you will not enjoy the treatment given by the bank. It depends on whether you have signed a contract with the property company according to the requirements of the bank. If the rights protection contract has been signed, it will be more troublesome. If it has not been signed, it is recommended to seek the opinions of the labor bureau. If the Labor Bureau can't help you, you'll have to go to court to sue the bank!