Decapitation operation has existed for a long time in military history; however, it was not until March 2003 'decapitation attack' became a well known term in the mass rnedia. This paper is based on the connotation of decapitation based on historical study and refines the term into military strategic concept of decapitation strategy. Ideas derived from detailed studies on Lanchester-type combat models are used to describe the effectiveness of conventional regular forces under decapitation warfare, which includes asymmetric, nonlinear, stand-off and special operation forces (SOF) operations. A conceptual model is presented to describe the effects of the decapitation strategy on the regular battlefield. With extensive coverage of operational factors such as robustness of forces, time difference between combats, undermining effects, breakpoints, attrition rates, total force level and force allocation, the model is suitable to analyse complex scenario with different types of military operations consisting of decapitation strategy. An illustrative example is provided to demonstrate the application of the model. The conceptual model is built based on hypotheses, assumptions, and criteria. In the absence of historical data, no data analysis and parameter estimation are involved.