Abstract: Mechanical equipment often operates in complex environments and is often affected by non-stationary working conditions such as time-varying loads， time-varying speeds， and transient shocks， resulting in failures from time to time. Time frequency analysis technology can take time and frequency into account， and has been widely used. However， the traditional time-frequency analysis method has a contradiction between the improvement of the aggregation and the reduction of the cross term. In order to realize the fault diagnosis of mechanical equipment in complex environment， Iterative Time rearrangement Synchrosqueezing Transform method is extracted. Firstly， a new group delay estimation operator is constructed based on Timerearrangement Synchrosqueezing Transform， and then a sharper time-frequency representation can be obtained by only one rearrangement operation. The effectiveness of the proposed method is verified by simulation signals and accelerated life test data of rolling bearings。