Abstract: Abstract: In order to solve the problem of equivalent spray thickness of dry and wet shotcrete and provide a reference for wet shotcrete design, the relationship between the outer radius of the sprayed layer and the strength of the shotcrete are built under the same support strength on the basis of the Lame solution of the elastic mechanical cylinder. And combined with laboratory test and a engineering example for calculation.The results show that the strength of shotcrete is negatively correlated with the outer radius of the sprayed layer under the same support strength.Using wet shotcrete can reduce suitable spray thickness.