Abstract: Sound field in rooms at low frequency can be simulated by using finite difference time domain method,which expresses the acoustical wave equation in a serial spatial and time iterative equation groups.In the paper,the basic principle of finite difference time domain method is introduced.It is emphatically discussed that the processing method of boundary condition and the application of using finite difference time domain method to room acoustical field si-mulation.The existing problems and prospective of this method are also analyzed.