In response to the shortcomings of using a single sensor for target tracking, a data fusion method for target tracking by radar and optical tracker is proposed in this paper. Based on this method, a strategy for removing false targets in radar images is presented to reduce the impact of sea clutter and noise on radar target tracking. A multisensor target tracking data fusion algorithm based on the principle of least squares is proposed to achieve data fusion between radar and optical tracker. Based on this algorithm, a track resumption strategy is proposed to reduce the occurrence of track interruptions during target tracking. Under three different maritime working conditions, the target tracking data from radar and optical tracker were fused via the fusion algorithm. The results show that the fusion data of target tracking are more accurate and stable than the tracking results obtained by a single sensor, verifying the effectiveness of the method proposed in this paper.