The invention discloses a method for switching all to high-speed group data (HRPD)network, and a relative system, wherein the method comprises that when a multimode terminal processes call in a non-HRPD network, the base station in the non-HRPD network sends a switch request carrying a multimode terminal mark to an access network deice AN in the HRPD network, AN receives the switch request, to build a data chain connection in the HRPD network, the multimode terminal via the built data chain connection processes the call continuously in the HRPD network. The invention builds a data chain load in HRPD network when multimode terminal processes call in non-HRPD network, to reduce switch time delay, avoid conversation interruption of multimode terminal, and confirm communication continuity.