The impact of blasting effect is an important factor of dynamic stability in the excavation of rock slope. Based on the sub-grade engineering in Jin-hai Lake of the New Countryside Construction Project, this paper sets up a finite element analysis model for the dynamic response of the cutting slope under the blasting loading. It discusses the stress field, displacement field and the propagation law of the blasting seismic wave, and analyzes the security evaluation criteria of the dynamic stability of cutting slope. What’s more, it makes a systematic analysis on the effects of blasting excavation on the stability of the cutting slope according to blasting vibration monitoring. The research provides referential value to form a correct understanding towards slope damage caused by blasting excavation.