The invention discloses a plasma etching method for showing defect of a cadmium zinc telluride (CZT) infrared substrate, and relates to the material testing technology of the photoelectric probe. The plasma etching method adopts the technical scheme that the defect of the infrared CZT substrate is shown by enhancing the reactive ion etching (RIE) with high-density low-energy inductively coupled plasma (ICP), so the method skillfully utilizes the accuracy controllability of the etching rate of the ICP-enhanced RIE and the inconsistency at a normal region and a defective region of the infrared CZT substrate and thus effectively solves the problems of uncontrollable substrate removal rate and blurred outline of the defect existing in a conventional defect showing method. The method has the characteristics of simple process, high stability and clear showing.