The number of eco friendly vehicle, which is using green energy such as natural gas(NG) and hydrogen(H2), is rapidly increasing in the world. Almost all of the car manufacturers are adopting the pressurizing fuel method to storage gas. The fuel storage system which can pressurize the fuel as high as possible is necessary to maximize the mileage of the vehicle. In Korea, the most important issue is that makes sure of safety of the fuel storage system, and several tests are performed to verify safety of the composite cylinder especially for Type 3 and Type 4. In this research, an empirical study on the internal temperature change of Type 3 and Type 4 composite cylinder during filling is performed by gas cycling test equipment. In order to measure the temperature, totally twelve sensors(every four sensors on the top, middle and bottom) are installed in each cylinder. As a consequence, large amount of compression heat is generated during rapid filling, and the result, temperature change in Type 4 is greater than Type 3, is confirmed depending on property of the liner material such as thermal conduction and thickness of carbon composite.