Abstract: In complex perforation operation，one of the most important factors that influence the bottom hole pressure and the effectiveness of high energy gas fracturing is the interaction between control fluid and high energy gas.The precise design of the height of control fluid determines whether or not complex perforation can success.In this paper，the flow characters of control fluid from the ignition of gunpowder to fracturing completion is simply analyzed，the motion differential equation is derived，the change of bottom hole pressure is comprehensively studied，upwelling of control fluid，and energy loss in the process of complex perforation separately are studied，too，thus，the judgment method of composed perforation effectiveness is put forward.Last，case study proves that the rational design of control fluid is the critical factor in the complex perforation design.

Key words: control fluid, gas-liquid interaction, bottom hole pressure, energy loss, mathematical model