Abstract: Deployment in wireless sensor networks(WSNs) is discussed and analyzed as a disk coverage problem.The theorem is proved that the maximum coverage is 82.7% when three sensors with the same sensing range are deployed as an equilateral triangle whose side is√3.The sensors are supposed as the particles in potential field,in which deployment of the sensors is adjusted by the virtual force.A deployment algorithm Coverage Efficient Virtual Force Algorithm(CE-VFA) is presented and simulated on Matlab.The results show that CE-VFA can improve coverage degree and coverage efficiency with less energy consumption,and the coverage degree can be improved more than 90%.