Data is an important basis for decision-maker to analyze problems.The data quality straightly affects the scientificalness of statistical analysis and the correctness of policy-making. The article proposed a method of data quality assessment based on cross-validation and established the optimal model of cross-validation to assess data quality in criterion of the minimum mean square error. Finally, through the empirical analysis of Chengdu domestic water consumption,the results indicated that the use of cross-validation method made the assessment of data quality more reasonable and conformed the actual situation.