To achieve the detection targets of the helium (He) lidar system and to measure the density of He atoms of the atmosphere at altitude of 200-1000 km, the parameters and performance of the He-density detection lidar system are designed, which mainly includes laser emitting part, optical receiving part, data acquisition and control part. According to the parameters of the He lidar, the relationship between the expected number of photons received and the distance under the conditions of different metastable He ［He(23S)］ densities, integration time and range bin is compared, in which it is found that the density of metastable He(23S) has the greatest influence on the signal intensity. The resonance fluorescence signals by Rayleigh scattering signals is calibrated at a common lower altitude to obtain a relative number density curve and signal-to-noise ratio (SNR) curve. The simulation results show that in the height range of 250~530 km, the relative error is less than 2% and SNR is more than 40 when the integration time is 30 min, the range bin is 50 km, and the density of He(23S) reaches the minimum. These results prove that the designed parameters of the system meet the detection requirement of He atom density in upper atmosphere and have certain reference value for the system implementation in the future.