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Abstract：The meteorological loss and non-meteorological loss in near space communication channel are theoretically analyzed. In addition, the modeling methods of channel propagation characteristics such as atmospheric absorption loss, rainfall attenuation and multipath fading are studied, and then a near space channel model is established. A software-hard combination implementation scheme of the near space channel simulator based on central processing unit (CPU) and field-programmable gate array (FPGA) is proposed, and the realization method of doppler shift and hilbert transform is analyzed. Combined with the actual signals generated by satellite navigation simulator and signal generator, the performance index and statistical characteristics of channel simulator are tested. The experimental results show that the statistical characteristics of the output channel fading of the channel simulator are consistent with the theoretical results, and the channel simulator can achieve multipath relative delay with resolution and maximum value of 5 ns and 5115 ns, and doppler frequency shift with resolution and maximum value of 1 Hz and 1.6 MHz, respectively. The channel simulator can assist in analyzing the influence of near space channel environment on signal propagation.