Water pollution is one of the great issues in today''s society. The paper analyzed the application of remote sensing technology especially with NDVI and water quality change trend in Weihe River valley in Shaanxi Province. The result indicated that water quality is one of the important factors which influence the growth of plants. The extremum of vegetation index went down in Weihe River valley, witch reflected that water quality turned into integral downtrend from 1998to 2008and pollution is more serious on high levels. The paper confirmed the feasibility of remote sensing technology to conduct water quality monitoring.