In marine target detection, a target could be lost by a mid-infrared detector if it’s located in sun glint area. Aiming at this problem, a real-time mid-infrared polarization imaging system employing a Wollaston Prism was designed which utilized the polarization characteristics of sun glint. The Wollaston Prism enabled beam separation into ordinary and extraordinary rays which vibrate at two orthogonally polarized directions, and two images were acquired on the same detector plane with light focused by an imaging lens. Degree of polarization of the target scene could be calculated and assist to detect marine targets. It enables effective sun glint suppression and marine targets detection.