This paper is based on the construction of the infrared static parameter test systems,which is designed to test modulation transfer function (MTF) of IR imaging systems. The fundamental theories of the canted slit-method to the measurements of MTF are analyzed. The testing method and steps are also given.After analyzing the method of data processing, the testing results and compared data corresponding to this method are provided. At last, the factors that influence accuracy and characters of the test system are also discussed.