In recent decades, urban floods have gained special importance because they can cause irreparable human and financial losses if they are not controlled and managed. For this reason, the design of an efficient runoff collection system that can both collect the runoff resulting from heavy rainfall and optimally use the rainfall, especially in arid and semi-arid regions, becomes very important. In this research, the urban runoff of Valiasr town (Aj) located in Baghin city of Kerman province was first simulated by analyzing rainfall data and location data in the SWMM software, and then the urban runoff collection system for the studied area for floods with a return period of 10 years according to the guideline number 118-3 was designed. The investigation to evaluate the efficiency of the system indicated that the system designed is efficient to pass the 25-year and the 100-year flood according to the mentioned guideline by making changes in the components of the system. The flow’s Froud number in the system’s links has not exceeded 1 and the maximum flow’s speed has not exceeded from allowed speed determined in the guideline, which is 3 meters per second. In order to reduce the produced runoff and achieve a more optimal system, green roof was used as a low-impact development method, and the results indicated that using this method reduces the amount of system outflow by 30%.