A method for controlling policy information required by a requested service includes: obtaining a second decision result of a second network on policy information required by a requested service; making decision on the policy information required by the requested service according to a first policy information in the first network and the second decision result; and generating a final decision result on the policy information required by the requested service. A device and a system for controlling policy information required by a requested service are further disclosed. If different networks have different related policies, solutions provided by the present invention may provide a process for controlling policy information required by a requested service.