The residual error generator of system is designed based on least square support vector regression（LSSVR）

and the parameters of LSSVR are optimized by genetic algorithm（GA）.The states of system can be identified effectively through the residual error generated by residual error generator.The results of simulative experiments show that the dynamic character of system can be simulated accurately by LSSVR based on genetic optimization

and accurate fault residual error can be generated.The veracity of fault diagnosis is guaranted effectively.