Abstract: With the transformation of the new power system for high proportion renewable energy, the system operation characteristics are becoming more and more complex. The coupling of transient angle stability (TAS) and transient voltage stability (TVS) occurs frequently, which brings about severe challenges to the system security and stability assessment. Firstly, the variable size dichotomy is used to construct the stability boundary between the TAS and the TVS by the PSASP. Meanwhile, the effects of the different fault locations, the induction motor proportion and the load rate on the stability boundary are studied, and the dominant instability mode is determined based on the boundary. Secondly, a new method for the power system TAS and TVS margin evaluation based on the attention mechanism and the one-dimensional convolutional neural network (1D-CNN) is proposed. This method takes directly the advantage of the measured data, using the voltage, the active power and the reactive power data of node as the input characteristics, which saves the data processing time. The 1D-CNN is adopted to construct the mapping between the input features and the limit resection time, and with the attention mechanism the prediction effect of the model is further improved. Through the analysis and verification of the New England IEEE39 bus system, the results show that this method realizes the rapid evaluation of the transient safety margin and has a high prediction accuracy.