Is it illegal for 360 to transfer the contract to Sichuan Lin Hang Company privately?

It's not illegal. If the transfer of the contract requires the consent of the other party, it should be approved and registered first, and the corresponding procedures should be handled according to its provisions. It is illegal to transfer the contract to Sichuan Lin Hang Company without permission, but it is not illegal. Contract assignment, that is, the change of the subject of the contract, refers to the transfer of all or part of the rights and obligations of the contract by the parties to a third party.