Blasting directional slippage method（BDSM） is a new silt replacement method . It can be widely used to build hydraulic projects（for examples: bulwark，dock and so on） in thick silt. The mechanism of BDSM is introduced. The structure of silt around and under bulwark is destroyed by shock and vibration of explosive blasting in silt. And the silt strength would be dropped because of the pore water pressure rising. It is very difficult to resume the silt’s strength in a short time. All these are conditions of riprap directional slippage，the silt would be replaced by riprap. Taking the engineering in Shenzhen-Hongkong western corridor as an example with BDSM on thick silt，the control standard of implementation quality and quality examination results are put forward. The results show that the method is effective.