The present invention relates to a policy resolution method and system, access network and terminal device for enabling modular network-assisted policy resolution, wherein the policy resolution is divided into separate stages each handling specific types of trigger events and performing specific types of policy actions. The separate stages are processed in a chronological order during a policy resolution round, and trigger events which occur during a policy resolution round are frozen until the start of the next policy resolution round. Thereby, modular policy resolution with reduced delays and oscillations can be achieved. Moreover, policy processing can be divided into a policy decision point functions in the network and a policy enforcement point function in the network or terminal device, so that terminal resources used for policy resolution can be saved.