Abstract: The accurate location of the forced oscillation（FO） source plays a significant role in secure and stable operation of power systems. However, due to the observability and time-varying characteristics of FO modes, the traditional methods are difficult to effectively extract the FO components from multi-channel measurement information, reducing the accuracy of the FO source location methods based on the dissipation energy flow. To address this issue, a time-frequency domain location method based on the dissipation energy flow for power systems is proposed. Firstly, the short-time Fourier synchrosqueezing transform（FSST） is applied to process the multi-channel measurement information from buses, constructing a unified time-frequency coefficient matrix of buses based on the information correlation among the measurement channels of buses. Secondly, according to the energy characteristics of the FO components, the time-frequency domain energy is used to screen and synchronously extract the timefrequency domain FO components from the time-frequency coefficient matrix. Furthermore, based on the time-frequency domain characteristics of the measurement information, an FSST-based time-frequency domain dissipation energy flow calculation model is derived based on the traditional time-domain FO dissipation energy flow calculation model, and the energy characteristics of the dissipation energy flow in the time-frequency domain are used to locate the FO source during the FO period. Finally, the proposed FO source location method is applied to the WECC 179-bus test system and WECC 240-bus test system as well as the actual oscillation event in New England, USA. The obtained results show that the proposed time-frequency domain location method can quickly and precisely locate the FO sources.