A GPU-based human body microwave echo simulation method includes: transmitting emulation input parameters from the memory of a CPU host into the display memory of a GPU device; configuring, at the CPU host, parallel computing network parameters to be run at the GPU device; initiating a kernel function for human body microwave echo simulation preset in the CPU host; computing the kernel function in parallel, in a plurality of processing kernels of the GPU device, in a multi-threaded manner, according to the parallel computing network parameters, to obtain simulation echoes of human body microwaves; transmitting the obtained simulation echoes of human body microwaves from the GPU device back to the CPU host. The method makes full use of the characteristic that a GPU can perform parallel computing to accelerate the echo simulation process, greatly improving the real-time performance of echo simulation of a human body microwave scanning and imaging system.