In order to clarify the dynamic evolution mechanism of rock burst at the bottom of nitrogen drilling wells, a numerical model of gradually approaching fractures at the bottom of the well was established using the multi physics field coupling analysis software COMSOL Multiphysics 4.3. Based on the equivalent plastic strain corresponding to the initiation of micro fractures in tight sandstone rock masses, the CWFS (cohesion weakening and frictional strength) -DP (Drucker-Prager) cohesive force weakening friction strength criterion was applied. The dynamic evolution process of rock burst at the bottom of nitrogen drilling wells was obtained through parallel numerical calculations using the DP strength criterion and the Mohr-Coulomb (MC) strength criterion. The results indicate that as the wellbore gradually approaches the fracture, the dense sandstone matrix will exhibit two different modes of failure, namely, shear slip failure along the potential shear plane towards the wellbore and compression yield failure under stress concentration conditions through microshear, until the failure zone extends to connect to the low-pressure wellbore. The high-pressure gas and rock burst debris inside the fracture release a large amount of energy, resulting in bottomhole rock bursts. The research results can systematically explain the abnormal changes in monitoring parameters during drilling before and after the rock burst at the bottom of well X8-2, providing theoretical support for accurately determining the downhole conditions of nitrogen drilling, and providing a basis for timely and targeted countermeasures.