In the quality condition assessment of equipmenta diamond frame model of the index system is put forward in order to shorten the time for the condition assessment aiming at missions while improving the quality management efficiencycombat preparation efficiencyand the level of combat readiness.Thenthe characteristics of index convergence methods are analyzed.After thatthe index optimization model is built and the quality condition is preliminarily assessed based on Principal Component Analysis (PCA).Finallya numerical example is given to verify the feasibility of the method.The analysis shows that:PCA has strong superiority in original index feature transformation and incremental index processingwhich can improve the evaluation efficiencyand achieve optimized distinguishing of the state assessment indexes between normal state and state of combat preparation.