Aiming at poor valuing objectivity for indicator weight in sustainability assessment of water resources use (SAWRU), an indicator system and a projection pursuit evaluation model optimized by particle swarm optimization algorithm were structured for SAWRU, and then the method was applied to the SAWRU of Sanjiang Plain. The applied results indicated that the method not only avoided artificial disturbance when valuing indicator weight but also had the advantages of objective and precise assessment result, feasibility and availability. The assessment results showed that the sustainable grade of water resources use of Jiamusi, Shuangyashan and Jixi which located at Sanjiang Plain belonged to III, and the grade of the other regions of Sanjiang Plain belonged to IV. Thus, scientific water resource use scheme and reasonable socioeconomic development strategy need to be made based on the regional characteristics of water resources and socioeconomic development.