Alkali slag recycled concrete is a new type of concrete prepared by replacing cement with alkali excited cementing material and natural stone with recycled aggregate, which can effectively reduce the amount of Portland cement and improve the utilization rate of waste concrete. However, there has been no relevant research on its mechanical properties. In order to study the basic mechanical properties of alkali slag recycled concrete, the compression test, splitting tensile test and flexure test were carried out with the steel fiber replacement rate and the recycled aggregate replacement rate as the main test parameters.The results show that: With the increase of recycled aggregate, the cube strength f_cu, splitting tensile strength f_t and flexural strength f_w of recycled alkali slag concrete all decrease, and the reduction range is 30%, 10% and 15% respectively when the substitution rate of recycled coarse aggregate is 100%. The cube strength and splitting tensile strength of alkali-slag recycled coarse aggregate concrete with increase first and then decrease with the increase of steel fiber volume substitution rate. When the steel fiber volume substitution rate is 0.6%, the compressive strength and flexural strength reach the maximum value. The flexural strength of alkali slag recycled concrete increases with the increase of steel fiber volume substitution rate.