The invention discloses a big data integration system and method for a smart city. The method comprises the following steps: accessing various data sources, and caching the data sources in a data cache region; cleaning, mapping and converting data increments of the various data sources in the data cache region according to a preset unified standard format so as to obtain standard data; classifying the standard data to store in different types of storage regions of a standard data resource pool; and associating and integrating the data of the standard data resource pool according to basic elements of the smart city, constructing a basic element library, and establishing a business database according to business requirements on the basis of the basic element library. With the adoption of an element-based big data integration manner, the data in the smart city are subjected to associated integration according to the city elements, the element-based big data service is realized, and data sharing among departments is easily facilitated. Meanwhile, big data analysis can be conveniently performed based on the city elements, and big data services can be well performed for citizens, enterprises and the like.