Grout-enriched roller compacted concrete (GERCC) is a kind of RCC for resisting dam seepage, by applying cement grout to normal RCC and vibrating compaction. To research the slurry diffusion in GERCC, we establish a grouting model and analyze main factors influencing the effect of grouting. According to test results of grouting diffusion and by using multiple regression analysis, we obtain the influence of each factor on the test results and the quantitative relationship among various parameters. Through correlation coefficient analysis of independent and dependent variables in the formula, we find that the grouting diffusion is closely correlated with the grouting pressure of material subjected to injection and the single-hole grouting volume as well as water-cement ratio of slurry. Finally, the research results can be referenced for construction and technique improvement of GERCC grouting.