InSb Infrared Focal Plane Array (IRFPA) detectors have always occupied an important place in the medium infrared waveband. With the development of science and technology, it is urgent to find out a precision machining method for InSb single crystals. A precise Single Point Diamond Turning (SPDT) machine is used to make InSb crystal be thin. There are several variable parameters, such as spindle speed, cutting depth and feed rate etc, for SPDT machines. Through an orthogonal experiment, the optimal working parameters for single point diamond turning of InSb crystals are determined. By combining with the double crystal diffraction measurement, it is found that the damaged depth of cutted InSb crystals is less than 3 μm. This InSb device processing experiment shows that the SPDT technology meets users'' requirements and achieves good results.