Using digital waveform data recorded by Yunnan seismic networks,quality factor Q₀ values of three regions in Yunnan are obtained by the iterative grid-search technique,as described by Atkinson. According of regional seismic wave attenuation characteristics in Yunnan,the single M_L magnitude deviations of 47 stations are analyzed based on the magnitude deviation statistics. The results show that the overall Q₀ values of Yunnan are relatively low and significantly different with different regions. The higher value of regional Q₀ is 251.3 in region 1(located in the west of Yunnan),followed by a value of 216.9 in region 2(located in the east of Yunnan),a lowest value of 102.6 in region 3(located in the middle of Yunnan). The number of stations with single magnitude smaller than the average magnitude of the network is relatively large in the region with a lower Q₀ and the greater attenuation of S wave. Although non-elasticity attenuation of seismic wave is similar,the single magnitude deviations are different due to the different site amplifications of each station,when earthquakes occurred in same regions are determined by stations located in the same region。