Big data are a new force driving the urban economic transformation and development，a new opportunity reshaping urban competitive strengths and a new way to enhance the government's governance capacity. At present，related major cities of China have established comprehensive big data development strategies，deepened the big data industry and application through reform and innovation and improved the government's public service level and social governance capacity. This report combs the policy documents published by 31 major cities，and mainly investigates their similarities and dissimilarities in opening and sharing of government data，innovation of big data industry，application of big data to the government's public services and other areas by combining quantitative research，qualitative research and systematic comparative analysis. On this basis，we will provide corresponding suggestions.