Abstract: It is desirable to develop an effective method for detecting the small insulative underwater target for the marine exploration and development. In this paper, an electromagnetic field detection method based on the finite elements is proposed for the detection of small underwater insulative targets. The simulation is carried out by using the ANSYS Maxwell software. According to the calculated difference of the magnetic induction intensity with or without the target for different current values in the underwater wire and different water heights and depths of the object, it is shown that for the current as high as 200 A passing through the underwater wire, the simulated difference of the magnetic induction intensity is greater than 0.3 nT, adequate to determine whether there is a small insulative target in the sea area of 350 m×350 m×35 m.