收集整理了新疆地震台网2009～2014年的地震观测数据，利用多台和达法计算了新疆天山地区中小地震的波速比及其背景值。为了突出异常变化，分析了研究区内的波速比扰动值变化，同时回溯了天山地区7次中强地震。结果表明： ①天山地区波速比的背景值为1.70左右，自2013年开始，波速比的低值异常主要集中在天山中东段及普昌断裂附近； ②2011～2013年研究区内4次MS5.0以上地震前，震中位置波速比扰动值多数处于低值状态； ③7次中强地震前，震中及其附近区域波速比低值的地震事件占相应时段内总事件的比率大于60%，研究区内中强地震前波速比呈低值状态较明显。

Based on the seismic observation report data provided by Xinjiang Digital Seismic Network from 2009 to 2014，we calculated the wave velocity ratio and its background value for medium and small earthquakes by using the multi-station method in the Tianshan region，Xinjiang. This paper analyses the variation of wave velocity ratio disturbance value to highlight the anomaly and also trace back seven moderate earthquakes at research area. The results show that: (1)the background value of the wave velocity ratio is almost 1.70. The wave velocity ratio obviously decreased in middle-eastern part of Tianshan Mountains and the region near Puchang Fault; (2)the wave velocity ratio disturbance value is lower at the epicenter before 4 earthquakes with M≥5.0 from 2011 to 2013 of the study area; (3)before 7 moderately strong earthquakes，the earthquake events with low value of wave velocity ratio account for over 60% of corresponding total events near the epicenter. The low value of wave velocity ratio is relatively obvious before moderate earthquakes.

新疆地震科学基金(201404)及中国地震局震情跟踪定向工作任务(2015010122)联合资助