Abstract: Grouting technology with very strong practicality and wide application can be used to reinforce loose gravel soil layers and improve its anti-seepage and carrying capacity. In China, loose gravel soil layers are distributed in every province, especially in the southwest and northwest mountainous areas. At present, due to their typical dual medium heterogeneity, lots of natural disasters are easily induced in loose gravel soil layers under the actions of rainfall, earthquake and human activities, such as debris flows, dammed lakes, collapses and landslides, which not only destroy a large amount of farmland, but also cause very painful accidents, and then seriously affect safety of people's lives and property. Firstly, based on penetration grouting operational principle and grouting flower pipe technologies in this research, some grouting experiments of reinforcing loose gravel soil layers had been carried out by analyzing and selecting four important influencing factors (grouting pressure, water cement ratio of cement grouting, mean hole distance of side grouting holes in grouting flower pipe and porosity of loose gravel soil layers). After that, according to numerical analysis method and Minitab 16 software, interrelations among grouting reinforcement effect parameters (such as grouting amount, diffusion radius, diffusion height, compressive strength of grouting stone body, et al) of loose gravel soil layers and influencing factors were researched, and then corresponding prediction models of these effect parameters which contains grouting pressure, water cement ratio of cement grouting, mean hole distance of side grouting holes in grouting flower pipe and porosity of loose gravel soil layers also were discussed. What is more, these prediction models were validated by means of designing indoor grouting experiments. Research results show that: 1) cement grouting injected into grouting flower pipe from top injection hole flows into in turn loose gravel soil layers from top to bottom through side grouting holes, while a small amount of it finally flows out from bottom grouting hole; A whole grouting stone body with approximately cylindrical shape is formed as cement grouting from adjacent grouting holes is compatible in loose gravel soil layer. 2) Predicted values of grouting amount calculated by grouting amount prediction models are less than actual measured values from grouting verification experiments, while predicted values of diffusion radius, diffusion height and compressive strength of grouting stone body are all more than corresponding actual measured values. And then these predicted values of grouting reinforcement effect parameters calculated by prediction models have within 10% relative error with the actual measurement values by grouting verification experiments, but these differences values are admitted. Thus, these prediction models of grouting reinforcement effect parameters constructed in this paper may take grouting amount, diffusion radius, diffusion height and compressive strength of stone body of reinforced loose gravel soil-layers by grouting technologies as design basis. Therefore, these research achievements obtained in this research may not only provide theoretical reference for disaster prevention, reduction and mitigation of debris flow, dammed lake, landslide and collapse induced in the loose gravel soil layers, but also can provide technical support for actual grouting engineering of controlled loose gravel soil layers by grouting technology.