This application provides a signal receiving method and a terminal device, to improve user experience. The method is applied to a terminal device provided with a plurality of subscriber identification module SIM cards, the terminal device is provided with a plurality of receive antennas, and the method includes: switching from a first mode to a second mode when a channel environment of a first SIM card meets a preset condition, where the first SIM card is a SIM card configured to receive a high-priority signal, the high-priority signal includes a paging message, a system message, or downlink signaling in a signaling interaction procedure, and a quantity of receive antennas configured for the first SIM card in the first mode is different from a quantity of receive antennas configured for the first SIM card in the second mode.