The rapid development and wide application of big data not only brings great convenience to social development，but also profoundly changes the way of government governance. As the leader of social reforms，government should deeply understand the importance of big data management and establish special organizations to provide big data security to improve the efficiency of the management. In order to make the public further understand the current situations and differences of big data management of governments at prefecture-level or above，we will adopt the model and indicator systems to evaluate the maturity of big data management by governments. This paper puts forward the index system of Big Data Management Maturity Index for Government（DMMI），aiming to evaluate the performances and practices of governments at all levels on big data governance through quantifiable indicators. It also aims to improve the governments’ responsibilities of big data governance through indicator guidance as well as to enhance regional competitiveness and big data services. The index system of DMMI has five first-level indexes，including strategic planning，supporting policies，organizational structure，data opening，human resources，12 second-level indexes and 26 monitoring points. It mainly works for the evaluation of governments at prefecture-level or above. It strives to model the regional big data management and service levels. According to the total scores of big data management maturity，it classified the different regions at prefecture-level into three stages：single application，integrated application and deep integration.