Using the data of the digital network monitoring micro-earthquake cooperatively set up by China and France, the attenuation characteristics of the Q-value of coda of microearthquakes in the area along western Haiyuan fault near Songshan have been studied. The coda Q_c values on 7 frequency bands of 170 earthquakes have been calculated. The coda attenuation in the area can be represented by Q_c=52f^1.09. It is shown that this area is a highly tectonic activity area.