In the applications of mobile Wireless Sensor Network (WSN), since the sensing range of the sensor nodes is limited, the coverage analysis is a scan coverage problem for the target area. In this paper, a new scan coverage algorithm based on multi-objective optimization was proposed. In the target area, the double objective optimization strategy was used on path planning for a single mobile sensor node, which could maximize the coverage of the node and make scan coverage path to the shortest. Simulation experiments were carried out under the conditions with obstacles and without obstacles. Compared with the formation coverage algorithm for multiple nodes, the proposed algorithm can significantly reduce the mobile energy consumption while moderately reducing coverage rate.