In the mid- and far-infrared wavelength bands, it is relatively difficult to measure the homogeneity of materials because infrared materials are unable to transmit visible light; however, in recent years, the demand for the processing accuracy of infrared materials has become increasingly high, and thus the realization of an accurate measurement of the homogeneity of infrared materials is imminent.Among the current detection means, interferometry is widely used as a non-contact and high-precision detection means. The non-uniformity of infrared materials was measured, and a mid-infrared interferometer with a wavelength of 3390nm was used for the experiments. The precision and accuracy of the present interferometer are verified by measuring the same element by transmission method and verifying the results by flip-flop method. Meanwhile, a comparison experiment was carried out between the present interferometer and the Zygo interferometer on the element made of fused silica, and the results showed that the measurement accuracy of the present interferometer can meet the requirements. This study provides an important reference for the accurate measurement of non-uniformity of infrared materials, which has certain theoretical and practical significance.