Aimed at the problem of lack of prior information in the shaft-rate electric field envelope tracking, the basic requirement of ship shaft-rate electric field tracking on the sensor array was studied and a multi initial progressive update extended Kalman filter algorithm based on maximum likelihood selection was introduced. The state space model of ship shaft-rate electric field envelope tracking was established, and the horizontal electric dipole was used to model the ship′s shaft-rate electric field envelope; a multiple initial value model based on maximum likelihood selection was established. Next based on the signal characteristics of the envelope of shaftrate electric field, the requirement of sensor array arrangement was studied. Simulation results show that it is feasible to track ship by the envelope of shaftrate electric field. And it is required that the sensor array must be made up of at least three sensors, which are not in a straight line. Under the condition that the sensor array meets the requirements, the proposed algorithm can effectively solve the lack of prior information in the shaft-rate electric field envelope tracking, and it has a high practical value.