Power analysis is a non-invasive attack against cryptographic hardware,which effectively exploits runtime power consumption characteristics of circuits.This paper proposes a new power model which combines Hamming Distance model and the model based on the template value of power consumption in combinational logic circuit.The new model can describe the power consumption characteristics of sequential logic circuits and those of combinational logic as well.The new model can be used to improve the existing power analysis methods and detect the information leakage of power consumption.Experimental results show that,compared to CPA(Correlation Power Analysis)method,our proposed attack which adopt the combinational model is more efficient in terms of the number of required power traces. Power analysis is a non-invasive attack against cryptographic hardware, which exploits runtime power consumption characteristics of circuits. This paper proposes a new power model which combines Hamming Distance model and the model based on the template value of power consumption in combinational logic circuit. The new model can describe the power consumption characteristics of sequential logic circuits and those of combinational logic as well. The new model can be used to improve the existing power analysis methods and detect the information leakage of power consumption. Experimental results show that compared to CPA (Correlation Power Analysis) method, our proposed attack which adopt the combinational model is more efficient in terms of the number of required power traces.