Using pure tungsten as target, WO_(x)films were deposited on ITOglass substrate by DC reactive magnetron sputtering. Through the XRD and STM methods, its crystal structure and surface microstructureare analyzed, and the relations between electrochromic properties and microstructure are discussed. The experimental results show that either in the colored or in the bleached state WO_(x)film deposited by magnetron sputtering method in such a condition is amorphous, as well as it is in the deposited state. The electrochromic action makes the color of the film change reversibly, and consequentiallyalso makes the microstructure change reversibly. The injection or extraction of Li~(+)does not make the basic structure of WO_(x)film change greatly, but makes the surface appearancedifferent, as a result, the accumulatemode of radical clusters tends to be more regular and low-energy mode.