Abstract: Successive waveforms of the vertical component recorded by 888 broadband seismic stations of China Seismography Network in January, 2010 to June, 2011 are used to investigate the temporal and spatial distribution of ambient noise strength, and the images of ambient noise strength at the period of 10 s in mainland China are obtained. The temporal variation of ambient noise strength shows some seasonal and periodic characteristics. The maximum ambient noise strength occurred in January 2011 to March 2011. The spatial distribution images of ambient noise strength show obvious zoning features, which doesn’t correlate with surface geology, suggesting that noise field is stronger than site factors. The strength in southeastern coastal areas achieves the maximum and generally decreases toward to inland areas, and arrives at the minimum in the Tibetan Plateau. The zonal intensity distribution is probably correlated with ocean tides from the Phillipin Ocean and the Pacific Ocean. It also shows that the influence from the Indian Ocean seems little. However, the ambient noise strength increases in a certain degree in Xinjiang area, indicating that the main source of ambient noise in the western area of mainland China is not derived from the East and South China Sea, rather it’s from the deep interior of the Eurasian continent. The ambient noise strength obtained in this study can supply some references for the seismology research based on ambient noise correlation. Moreover, it can supply the basic data for the attenuation research based on ambient noise, and then achieves the object of retrieving the attenuation of Rayleigh waves from ambient noise.

Key words: Ambient noise, Amplitude of surface wave, Attenuation, Mainlan China