In this paper, an algorithm that aims at improving the coverage of Wireless Sensor Networks (WSN) is proposed. The coverage is improved in random deployment regions by employing some mobile nodes, which can actively move to desired locations. Coverage improvement is attained by incorporating Particle Swarm Optimization (PSO) algorithm tomaximize the sensing coverage area by finding the optimal placement for the mobile sensors that minimizes the overlap between the coverage regions of sensors. The continuous redeployment of the mobile sensor will decrease the uncovered regions and consequently improve the Quality of Service (QoS) of the network. Simulation results demonstrate the effectiveness of the proposed algorithm in increasing the coverage area.The performance of the proposed algorithm is compared with that of the exhaustive search gird based algorithm and results demonstrate that the proposed algorithm is competent for the dynamic deployment in WSNs and has better performance with respect to computation time and effectiveness than the grid quorum based node mobility algorithm.