According to the atmospheric continuous laser beam imaging technology, the corresponding resolution range for the distance between separated transmitter and receiver on bistatic helium lidar system is obtained, as well as the relationship between the single-row CCD pixels and the altitude, and the variation curve of resolution range with different altitudes. Moreover, the corresponding relation between the number of photons received by the system′s single-row pixels and the altitude under different metastable helium densities is analyzed, and the signal to noise ratio and relative error varied with altitude are obtained. The simulation results indicate that the signal to noise ratio can be improved by increasing the integration time. In the range of altitude from 400 km to 1 000 km, when the integration time is 2 h and the range resolution is 50 km, the signal to noise ratio is in the range from 10 to 65 and the relative error is less than 10%. These results prove that adopting the bistatic helium resonance fluorescence lidar system can detect the metastable helium density of the 200~1 000 km thermosphere, which provides a reference for further perfecting and optimizing the scheme of the bistatic helium resonance fluorescence lidar system.