Abstract: Special irradiation rig should be designed when a new type of nuclear fuel need to be irradiated and tested in the reactor. In the design of irradiation rig used in light water reactor, zirconium alloy is often be fabricated as component because of its small thermal neutron absorption cross section. When Zr-4 alloy tube is used as the high temperature bearing part of the irradiator, its long-term deformation under high temperature and high pressure should be considered to prevent its excessive deformation from affecting the thermal design of the irradiator, thus affecting the stability of the irradiation parameters and the safety of the reactor core. The working condition of irradiation rig is different from commercial pressurized water reactor, so there is not enough experience with it. The maximum temperature and internal pressure of the high temperature compression part during the irradiation can be obtained by calculation, and the verification experiment of the fuel element cladding made of Zr-4 alloy tube can be carried out out-of-pile. The experiment specimen made of Zr-4 alloy tube was charged to different internal pressures and heated to different temperatures by electricity. After a period of stability test, the change of its outer diameter was measured and repeated for 5 times. The experimental results of deformation caused by oxidation and creep were compared with those calculated by Leistikow-Schanz and Rosinger’s formulas, respectively. The results show that the calculated results of Leistikow-Schanz formula are about 15% larger than those of the experimental oxidation weight gain, while the calculated results of Rosinger formula are in good agreement with those of the experimental creep deformation, which prove the rationality of the experimental results. The Zr-4 alloy tube can be operated for a long time under the condition under 29.10 MPa wall stress and 460-470 ℃.