On the theoretical basis of cloud services, big data technology and case-based reasoning technology (CBR), the authors propose an Intelligent Approval System for City Construction (IASCC). The paper introduces the concept of ‘case approval cloud' and puts forward the city construction approval model based on CBR, by which the storage and computation of the urban construction approval data are concentrated in the cloud. In this system, the authors use the distributed database of HBase, making the data storage capacity of the system with high scalability, design the intelligent approval system based on CBR using the distributed programming framework of MapReduce, making full use of the large amount of historical approval data, and use the distributed full-text retrieval system of SorCloud to retrieve the approval data with a high response speed. IASCC adopts Hadoop as the development platform, using HBase, Solr and MapReduce technology to complete the prototype development of an intelligent approval system. Finally, the authors give the implementation of the system and the performance tests of some key modules.