Abstract: The optimal design of water distribution network is an optimization problem of functions that depend on a series of nonlinear discrete multi-variables.Many traditional methods are not satisfactory when applied in this field.This paper introduce a relatively novel algorithm,genetic algorithm(GA),which has special advantages in tackling this problem based on its inherent characteristics.This paper gives an overall introduction of basic principles of GA and analyzes the characteristics of water distribution system optimization design.A mathematical model is put forward.Some problems on the software solutions of several key GA operators and the hydraulic computation constraint factors are discussed.Lastly this paper chooses a case study to demonstrate the feasibility of GA in this field.It makes a comparison between two water supply schemes for a residence region.