Heavy tamping method is a kind of important method of rubble bed tamping in the construction, the heavy hammer tamping energy is an important indicator of impact compaction hammer effect, the hammer tamping energy can be influenced by hammer type, flow resistence, drop distance and other effects. Therefore, on the basis of fluid dynamics. First of all, establish the calculation model of the hammer in water movement, analyse the hammer flow resistance in the process of hammer in water movement, and then through the indoor shrinkage scale test, analyse the water movement law of the cylindrical and cone hammer,obtain the experiential tamping hammer water flow coefficient value. Finally, analyse of the different geometric rammer, different distance to the effect of compaction effect. The results show that a cone type tamping hammer and cylindrical rammer compared. Because of the chamfer of a cone type hammmer, flow resistence coefficient is smaller in water and the value is about 1.0. under the action of the same tamping energy, different types of hammer has difference in 5% on the rubble mound foundation compaction effect.with a hammer in different falling distance, the greater the falling distance is,the greater the amount of settlement of riprap foundation bed is, the bigger the compaction stress is. but rubble mound foundation settlement has a limit value. The research results can provide reference for the selection of hammer shape under the process of compaction.