A voice service processing method includes: sending, by a terminal device, a first message to a network device of a first network, where the first message requests a circuit switched fallback (CSFB) voice service; receiving, by the terminal device, a second message sent by the network device of the first network, where the second message instructs the terminal device to perform a network redirection; if the second message carries no frequency information, determining, by the terminal device, a redirection frequency, where the redirection frequency is a frequency supported by a second network; and sending, by the terminal device based on the redirection frequency, a connection request to a network device of the second network, to perform a circuit switched (CS) voice service.