In order to achieve the application of a large number of distributed controllable loads with small capacity to system frequency regulation, the acquisition of distribution system frequency for all controllable loads is a prerequisite and basis. A collaborative acquisition method of distribution system frequency based on consensus filtering is proposed, where only frequency-measuring devices at distribution substations are utilized. Limited communication between neighboring controllable loads/distribution substations can facilitate consistent, robust and accurate acquisition for system frequency signal for all controllable loads. Also this method can eliminate noise and reduce device costs. Convergence and robustness of collaborative acquisition method are proved by the theoretical analysis under the two situations with and without communication time delays. Simulation results based on Simulink demonstrate both effectiveness and feasibility of the proposed method.