Based on the three-component continuous seismic waveform data of 10 fixed stations in Tengchong volcanic network from 2020 to 2022, this study systematically studies the background noise characteristics of seismic observation in Tengchong volcanic area by using noise Power Spectral Density (PSD) and Probability Density Function (PDF) analysis methods. The results show that the high-frequency (> 1 Hz) noise of Tengchong volcanic network shows significant diurnal variation characteristics, and its intensity is highly consistent with the human activity cycle. The power spectral density of acceleration noise is about 20 dB higher than that at night due to the influence of industrial production, traffic and building construction during the day. Although the second type of microtremor noise in the 0.1~1 Hz frequency band originates from ocean waves, it is still the main noise component in the inland Tengchong area. The noise in this frequency band has obvious seasonal changes. The noise level in winter is about 2.5 dB higher than that in summer, and the peak frequency moves to the low frequency direction for about 1 s. Because the distance between each station is small and the distance from the coast is close, there is no significant spatial distribution difference in the noise of each station in the 0.1~0.5 Hz frequency band, but the noise level of the cave station is about 3 dB higher than that of the surface station. The analysis shows that the integrity of the cave bedrock may form a waveguide channel, which makes the energy propagate more efficiently in this frequency band, and the microtremor signal can be recorded more clearly. The results of this study have clarified the dominant factors of noise sources in different frequency bands of Tengchong volcanic network, revealed the influence mechanism of human activities, geographical environment and station installation mode on noise level, and provided an important theoretical basis for the optimization and transformation of the network and the improvement of data quality.