In order to study the strength characteristics and evolution law of concrete under the combined action of carbonization and sulfate attack, the influence mechanism of the strength characteristics of concrete is analyzed by means of single sulfate wetting-drying test, single carbonization test and carbonization and sulfate wetting-drying alternate test. The test results showed that: the smaller the water cement ratio is, the less the compressive strength and splitting tensile strength of the concrete are when the single sulfate attack and the interaction of carbonization and sulfate corrosion have taken place.With the increase of carbonization time, the compressive strength and splitting tensile strength of concrete begin to increase at first and then slowly, and the larger the water cement ratio is, the greater the growth rate is.Under the combined action of carbonization and sulfate attack, the influence of the two on the strength of concrete is not a simple superposition of their respective effects, but they affect each other and promote each other. Therefore, in the environment where carbonation and sulfate attack exist simultaneously, the water cement ratio of the concrete should not be too large.