Short-wave infrared (SWIR) band has excellent potential for imaging. Owing to the focal plane detection arrays, SWIR plays an increasingly important role in modern society. Aiming to solve the defocus problem of SWIR imaging and improve its applicability, a wavefront coding system is introduced into the SWIR band. For light and small SWIR imaging, a cubic phase mask is placed at the pupil to extend the depth of field. The phase mask parameter is converted into radial coordinate coefficient, which is optimized by the consistency of the modulation transfer function and image recoverability. Leveraging 640 pixel×512 pixel SWIR images to simulate the wavefront coding system, and the blurred images are restored through the classic Lucy-Richardson algorithm. The optical design and simulation results show that the wavefront coding system effectively reduces the sensitivity of SWIR imaging to defocus within at least ±20 times the depth of field, and the peak signal-to-noise ratio of the restored image reaches 38.5038 dB.