The massive air-conditioning loads on the customer side are considered one of the important frequency regulation reserve resources for the power system. By aggregating these air-conditioning load resources, frequency regulation services can be provided to a power system to improve system frequency regulation capability. Therefore, a control strategy for the coordinated participation of fixed-frequency air-conditioners (FFAC) and inverter air-conditioners (IAC) in frequency regulation is proposed. Based on the different load characteristics of the two types of air conditioners, a FFAC cluster simulates the droop control of the turbine governor. When a deviation from the nominal system frequency is detected, a certain number of devices are turned on or off to change the FFAC cluster’s operating power and participate in frequency regulation. The IAC cluster adopts the proportional-integral control to continuously adjust the cluster’s power by adjusting the operating frequency of the air conditioning compressors to participate in frequency regulation. On this basis, the frequency regulation models of the two types of air-conditioning clusters are extended to interconnected multi-area power systems. The inter-area tie-line deviation and intra-area frequency deviation are used as feedback control signals to further optimize the air-conditioning loads regulation strategy. Finally, simulation results verify the effectiveness of the proposed coordinated control strategy.