Abstract: This study carries on the hydrologic analysis and develops the planning procedures to determine the storage capacity of the rainwater retarding practices for the urban flood mitigation after development.The planning procedures employ the concept of the on-site control and the distributed management of small-scale rainwater retarding facilities.The computational procedure for determining rainwater retarding practices is also demonstrated by an example The conventional urban flood control method procedure is only to maintain the pre-development peak runoff by installing the detention ponds at downstream However, the procedures developed by this study can maintain both flood peak and the volume of the pre-development with less volume compared to conventional one.