Abstract: At present, the suitable mix proportion design experience for rich slurry cementing sandy gravel is insufficient. Based on the diamond belt theory of "double gradation and double strength" and the design criterion of cementing material strength, the influence of the parameters change of cementing material dosage and water-cylinder ratio on the rich slurry cementing sandy gravel strength were studied by orthogonal compressive strength test and extreme difference analysis. The optimum mix proportion of fine gradation and average gradation rich slurry cementing sandy gravel under the normal mixing process and adding slurry mixing process were obtained. The results showed that the average strength of normal mixing cementing sand gravel at the same design age of 28 d、90d was larger than that of adding slurry cementing sand gravel, the former is about 1.60 to 1.78 times of the latter.