Abstract: This paper introduces the test methods of heat expansion coefficient of the pipe of carbon fiber/ epoxy composite by a micrometer at low temperature for the radial direction and axis direction of the pipe.For the dissimilarity directiont,he test devices are different.Described the test process and regulations,point out that carried on heat expansion test to the pipe,shouldn’t adopt traditional method taking out the small a piece of sample from the pipe,because of the method exists the bigger the rror compare to the test of pipe.The regulation and influence factor of the heat expansion of the pipe have been discussed at low temperature and the error influence factorss,uch as a pole,temperatures etc.,have been analyzed,and the solved method were been afforded.For many times test,the heat expansion coefficient of the pipe of carbon fiber/ epoxy composites change into small graduallya,nd the fact were been researched and analyzed at first step.Some date of the heat expansion coefficient of the pipe of carbon fiber/ epoxy composite at a specifically technics have been given.