Nowadays, researches for replacing material systems for cryogenic propellant tanks by composites have been being performed for the purpose of light weight of a launch vehicle. In this paper, a type III propellant tank, which is composed of the composite developed for cryogenic use and an aluminum liner, was fabricated and tested considering actual operating environment, that is, cryogenic temperature and pressure. For this aim, liquid nitrogen (LN2) was injected into the fabricated tank and in turn, gaseous nitrogen (GN2) was used for pressurization. During this test procedure, strains and temperatures on the tank surface were measured. ESG (electric strain gage) and thermocouple were used for the measurement of strain and temperature, respectively. Delamination between hoop layer and helical one, was detected during the experiment. Finally, Tsai-Wu criterion for the tank and microscopy for the composite/aluminum ring specimen were carried out to investigate the reason why delamination had happened.