To investigate the influence of tensile stress on the salt-freeze resistance of hydraulic concrete, salt-freeze tests were conducted under ultimate tensile stresses of 0%, 30%, and 50%. The mass loss, attenuation of dynamic elastic modulus, and chloride ion diffusion laws were analyzed, and the damage mechanism was revealed in combination with pore structure evolution. The results indicate that tensile stress significantly accelerates the deterioration process of concrete. Under ultimate tensile stress of 50%, after 200 freeze-thaw cycles, the mass loss rate of low-air-content concrete specimens increases by 21.7%; the relative dynamic elastic modulus decreases by 35.5%, and the chloride ion diffusion coefficient increases by up to 47.0%. Microcracks induced by tensile stress significantly enlarge the pore size and enhance the pore connectivity. Although increasing the air content can mitigate salt-freeze damage, the proportion of harmful pores in high-air-content concrete is relatively high, and the superimposed effect of tensile stress may affect the durability of concrete.