Abstract: In order to research the complex stress of helical transferring heat tube of SG in SMART reactor under operating condition, confirm the largest equivalent stress position and analyze the impact of heat stress on the helical transferring heat tube, the finite element software ANSYS was used for thermo-fluid-solid coupling analysis in helical transferring heat tube of SG in SMART reactor, and the resulting stress, strain and deformation of the tube were calculated. The results show that the maximum values of stress, strain and deformation depend strongly on the temperature of the system.