How to evaluate the stereoscopic video quality accurately and effectively plays an important role for the development of video communication system. We propose a stereoscopic video quality assessment method which focuses on the structure information extracted from adjacent frames of single view. Spatio-temporal structural information is sensitive to both spatial distortions and temporal distortions. For two views of stereoscopic video, we firstly calculate spatio-temporal structure based local quality according to spatio-temporal gradient characteristic and chrominance information, and these local quality scores are integrated to obtain frame level scores for single view. Then, we use energy ratio map of two views as weight values to fuse the two view scores into single frame score. Finally, all the frame level scores are combined via asymmetric tracking effect. Experiments on NAMA3DS1-COSPAD1 database demonstrate that the proposed method achieves highly competitive prediction accuracy and delivers very low computational complexity.