Based on the characteristics of combustible cartridge case, a test method for heat-resistance time of minor-caliber rapid-fire gun with high rate of fire is proposed and test apparatus prototype is developed. The method is to do the flame detection through the use of photomultiplier tubes combined with optical fiber and detecting smoke by using the infrared and receiver combined with optical fiber. The test experiments show that the apparatus can effectively test the signal smoke and flames. Moreover, it can be applied to the heat-resistance test of other nonmetallic materials.