Abstract: Using the observation data of five VP vertical pendulum tiltmeters in Inner Mongolia from 2019 to 2021, we analyze their background noise level in the seismic frequency band (200~600 s) by calculating the seismic noise magnitude (SNM), based on the Power spectral density (PSD) analysis method. The results are as follows: (1) The noise level observed by the three instruments is low, while the noise level of the other two instruments is high, indicating that there is no obvious regulation in the regional distribution. (2) In the low noise environment, the observation curve is smooth and the earth tide is clear, in addition, the observation environment of the station is excellent and stable. (3) In the high noise environment, the observation curve has many burrs and not smooth, and the tunnel where the station is located in poor condition, which is disturbed by strong wind and vibration for a long time. In addition, one set of instruments has long-term observation system problems. By analyzing the background noise characteristics of VP vertical pendulum of different stations, the results could support site selection of the new instrument and the interpretation and analysis of the observation data.