Research on battle chain of observe,orient,decide,act (OODA) loop,with the graphical evaluation and review technique (GERT) network technology and triangular fuzzy number theory,the fuzzy evaluation matrix of battle chain activity parameters of OODA loop is established,and the F-GERT network model and the effectiveness evaluation model of battle chain of OODA loop are constructed.The effectiveness evaluation analysis process is also designed.Finally,taking a battle chain of OODA loop in air defense operation for example,the effectiveness evaluation method is verified,which provides theoretical support for evaluating the battle chain of OODA loop.