The invention provides a network switching method and system; wherein the method is applied in a dual-card terminal; a first card is in support of an LTE network; a second card is in support of a 3G/2G (The2/3th Generation mobile communication technology) network; the method comprises following steps of in a process that the dual-card terminal uses the first card to carry out an LTE call, determining that the dual-card terminal is about to execute an SRVCC (Single Radio Voice Call Continuity) switching process; applying CS domain network resources demanded when the dual-card terminal executes the SRVCC switching process, wherein the CS domain network resources are applied through the second card of the dual-card terminal instead of the first card; and when the dual-card terminal executes the SRVCC switching process, finishing the SRVCC switching process through adoption of the CS domain network resources applied in advance. According to the method and the system, the purpose of reserving the CS domain network resources demanded for executing the SRVCC switching process in advance is realized; the waiting time when the dual-card terminal carries out network switching is reduced; and call interruption of the dual-card terminal resulting from network switching is avoided.