In order to monitor the radar work condition and decrease the BIT monitoring points, a new optimization strategy based on multi-signal flow model is proposed. Introduces the definition and representation of multi-signal flow model, analyzes the method about modeling, predigesting dependency matrix, selecting monitoring points and designing diagnosis strategy by using this model. The validity of this method is verified in the radar’s 2km gate BIT circuit. The result shows that the method can reduces the complexity of monitoring system, avoids the blindness of diagnosis inference course, and raises the efficiency of fault diagnosis.