The invention discloses an optimization design method for a water supply pipe network behind a dam. The method comprises the following processes of in-bin pipe design, connection pipe design, intelligent water flowing system design, water supply pack design, dam-behind water supply main pipe design, water supply main pipe network design, water flow switching design, refrigerating water station design, pipe network monitoring and pipe traffic design. Through the system design of the water supply pipe network behind the dam, a more fine and intelligent water supply guarantee is provided, the efficiency and quality of water flowing and cooling of dam concrete can be significantly improved, and the technical problems of complex arrangement of pipe lines, many connecting pieces, unknowable operation status and inaccurate control of the water supply pipe network behind the dam in the prior art are achieved.