Abstract: This paper has expounded the types and characteriatics of the main influence facters on groundwater level dynamic state.According to the many years dynamic characteristics of groundwater level,we have presented three kinds of anomalies marks of mid-short term(one year scale)in groundwater level physical parameters and the principle for the optimum method to extract mid-shrot term naomalies by computer.Based on studies,the judging methods of mid short term anomlies for earthquake prediction have been analyzed,contrasted and optimized.Finally,five kinds of optimized extracting method of mid-short term anomalies have been produced in brief.