With the continual increment of system scale and the gradual complication of components， security problem of power grid has been a focus. Based on the existing researches， respective definitions and evaluation models of running state vulnerability and structural vulnerability are presented. Then a new evaluation method combining intensity of state variables and structural characteristics of components is proposed， and a corresponding evaluation model through which different assessment motives and results can be obtained in different state variables is established. Results of a numerical example show that the model can assess the vulnerability of power grid based on different state variables， and it has a preferable ability and precision in identifying the vulnerable components of power grid. The method can be a useful reference for power grid vulnerability assessment and operation and maintenance. Meanwhile， it is verified that the method is rational and available.