Abstract: In recent years, owing to its trade-off simulation accuracy and simulation efficient, the variable-grid method has garnered increasing attention. Based on the traditional variable-grid algorithm, this study proposed a multi-block and multi-stage method. First, we derived the mathematical formula for the false reflection error generated by the variable grid algorithm in the grid change area. By introducing the Lanczos filtering operator to enhance the stability of the algorithm, the error caused by grid changes can be reduced. Second, to simulate small cracks using traditional variable-grid algorithms, a large error and instability are often introduced under ultra-high grid ratio variations. However, by introducing a multi-stage condition to the staggered variable-grid method, we can achieve efficient and precise simulations with ultra-high grid ratios. Finally, to improve the simulation efficiency for an existing number of discrete target areas with different variable grid formats, we presented a multi-block variable grid to conduct different multiples of variable-grid simulations in each region.