Flood severity and frequency have grown over the years as a result of urban development and climate change. Floods in cities cause major challenges such as property and infrastructure damage, transportation congestion, loss of life, environmental threats, and health concerns. To relieve the load on the urban drainage system and prevent flooding, effective measures to strengthen its resilience are required. Traditional design methods, which rely on past performance trends and long lifespans, usually result in infrastructure that is inflexible and unable to adapt to changing situations. Those traditional studies focused on drainage design, such as pipe slope and diameter optimization, coupling design cost limitation. Furthermore, various terminologies for the overall concept of green/grey infrastructure have been proposed in the literature. Some studies have been focused on the optimization of the suitable locations for storage tanks, which would be one of the most efficient approaches. Building storage facilities such as retention or detention basins are a cost-effective and efficient structural option to improve the resilience of urban sewerage system, reducing peak runoff in existing drainage systems in urban areas, especially compared to traditional methodologies such as increasing pipe diameter or slope providing sufficient hydraulic capacity. The basic concept is to create an optimization framework using Non-dominated Sorting Genetic Algorithm II (NSGA II), coupling with hydraulic model SWMM, and use it to change a number of drainage system-related variables such pipe diameter, slope, and storage unit size. The main idea of the optimization framework in thesis is to combine different methods into one framework, which is a challenge in a complex system due to the dilemma between the resilience objective and financial limitation. Literature review would shows that the recent research in terms of sewerage system resilience optimization utilizing different methodologies. Application of the system would shows that optimization model has the capability to improve the resiliency of urban sewerage system. The main objective of the thesis are (i) develop a new framework to optimize volume and location of storage units in urban drainage systems; (ii) develop a two-stage multi-objective optimization framework; (iii) develop the new index to make the optimization process feasible.