Abstract: In this paper, due to the presentation of an algorithm procedure combined with h -adaptive integration procedure based on the high-performance parallel computing framework JASMIN, a symmetric positive semi-definite subgridding finite difference time domain (FDTD) method was developed with the ability of large-scale parallel computation, overcoming the bottleneck problems of computational efficiency in engineering practice, and making FDTD method achieve large-scale parallel computation capability. Retaining the advantage of good parallel expansibility of FDTD, the arithmetic was arranged to dissect the fine structure of a large-scale model based on refined locally meshes, and support the iterative computation simultaneity with smaller time and longer time steps separately in the region of different refined meshes. Numerical examples show that the proposed method has good parallel scalability, and can ensure the accuracy and stability of numerical results. Compared with the traditional FDTD method, it can significantly reduce the memory requirements and improve computational efficiency.