Research on the threat assessment of battlefield is the key step for better understanding the operation strength and combat intention of operational object. Based on the method of operational area layered and hypothesis of threat ability equivalent, evaluate the threat of weapons in different layers, then according to the degree of threat of weapons in different timing to evaluate the threat assessment of battlefield. The results shows that the method can effective avoid the ambiguity of traditional method and offer some suggestions for operational force to adjust distribution based on the degree of threat.