To enhance quality and utilization of radar,use free surface optical (FSO) lens and imaging technique are used to develop starfi sh shaped submarine small laser radar.Using micro-into-space multi-focus FS O lens and imaging plane,the lens and imaging structure of Cassegrain telescope are designed.The differentia l equation of laser radar lens and imaging plane is built.The variation curv e of free surface focal power is solved.The free surface reconstruction technology of reverse engineering is used to achieve the 3-D data of free surface lens,then the free surface lens and imaging plane are reconstructed.The panoramic detection is realized,and the problem like detection for facilities of sea bed is solved.The method of FSO lens based starfish shaped submarine small laser radar is feasible,and can enhance the quality and utilization of radar.