Although magnetic reconnection is believed to be a key process in solar flares, the flares' triggering mechanism remains a long-standing problem. In order to resolve this issue, the physical linkage between the magnetohydrodynamic (MHD) process in the macroscopic scale and the plasma kinetics in the microscopic scale has to be understood. Multiple-scale simulation, which can precisely describe the nonlinear process of the MHD equations as well as the complexity in the solar corona, will play a crucial role in this field of study.