Credit rationing issues exist in the credit process.Exploration of personal credit scoring has solved and optimized the credit rationing biases through mathematical induction.Micro-structural analysis is presented for personal credit scoring.Utility analysis of it is proposed in dimensions of information asymmetry，adverse selection and ethical risk.The study offers important insight toward the integral mechanisms of credit scoring optimization for credit rationing.In addition，to solve the problems of credit rationing in micro aspects，optimizations of index system and sample structure are analyzed.