Based on the power quality disturbance problems of the power system connected with micro grid, The detecting method of transient power quality disturbance is mainly studied, which based on lifting wavelet transform, after the analysis of lifting wavelet construction principle, the transient power quality disturbance detecting method based lifting db4 wavelet is put forward, the results of simulation and comparison analysis prove that the method can detect and locate the transient power quality disturbances quickly and accurately, so that ,an effective and feasible method is provided to the research of transient power quality disturbance problems brought by the connection between micro grid and power system.