Abstract: The Failure of a partial cylindrical shell structure and its effects on the stability of the macroscopic structure involve the multiscale mechanical problems in bridging macroscopic and mesoscopic scales. The multiscale algorithm of element/mesh momentum transfer was deduced, and the multiscale numerical method of time and space by coupling three-dimensional DEM (Discrete Element Method) and cylindrical shell FEM (Finite Element Method) was established. Validated by the simulations in the partial failure of the cylindrical shell subjected to inner pressure and surface laser irradiation, this multiscale method could perfectly accomplish multiscale time and multiscale space computations synchronously, which not only simulated the mesoscopic heterogeneous evolvements of the partial cylindrical shell and their effects on the whole cylindrical shell accurately, but also consumed a little computation time and exerted the advantage of high efficiency of multiscale simulation effectively.