Automated parking systems, which automatically park and retrieve vehicles, have been steadily replacing conventional parking systems. The spiral parking system is a type of automated parking systems that has round shaped parking tower. It has many advantages such as efficient space utilization, improved vehicle safety, decrease in vehicle damages, and better control of vehicles. However, automated parking systems are very expensive to build and inflexible to future change and so very careful design of the system is justified. We develop an economic design model of spiral parking system based on a recursive optimization and simulation procedure. With the recursive procedure the dynamic nature of the parking system can be integrated into the optimization model. The optimal value of design parameters is found that minimizes the total cost while complying with the desired performance level of the system.