A dual connectivity communication method, comprising: receiving (810, S930, S1050, S1004), by a terminal device (60, 1200), or, a chip for the terminal device, indication information from a master node, wherein the indication information is used to indicate that a key used for signaling transmission performed between the terminal device and a first secondary node by using a second signaling radio bearer, SRB, is a first key, wherein the first key is a key used for signaling transmission performed between the terminal device and the master node by using a first SRB, wherein the master node includes a central unit, CU, and a first distributed unit, DU, and wherein the first secondary node includes the CU and a second DU; and determining (820, S940, S1060, S1005), by the terminal device (60, 1200), or, the chip for the terminal device, based on the indication information, that the key used for signaling transmission performed between the terminal device and the first secondary node by using the second SRB is the first key; wherein the indication information is carried in a radio resource control, RRC, reconfiguration message, and the RRC reconfiguration message is used to indicate the terminal device (60, 1200) to add the first secondary node, or used to indicate the terminal device to be handed over from a second secondary node to the first secondary node; wherein the RRC reconfiguration message further comprises a first value; and wherein the determining, by the terminal device (60, 1200), or, the chip for the terminal device, based on the indication information, that the key used for signaling transmission performed between the terminal device and the first secondary node by using the second SRB is the first key comprises: when the first value is a preset value, determining, by the terminal device (60, 1200), or, the chip for the terminal device, based on the first value, that the key used for signaling transmission performed between the terminal device and the first secondary node by using the second SRB is the first key. receiving (810, S930, S1050, S1004), by a terminal device (60, 1200), or, a chip for the terminal device, indication information from a master node, wherein the indication information is used to indicate that a key used for signaling transmission performed between the terminal device and a first secondary node by using a second signaling radio bearer, SRB, is a first key, wherein the first key is a key used for signaling transmission performed between the terminal device and the master node by using a first SRB, wherein the master node includes a central unit, CU, and a first distributed unit, DU, and wherein the first secondary node includes the CU and a second DU; and determining (820, S940, S1060, S1005), by the terminal device (60, 1200), or, the chip for the terminal device, based on the indication information, that the key used for signaling transmission performed between the terminal device and the first secondary node by using the second SRB is the first key; wherein the indication information is carried in a radio resource control, RRC, reconfiguration message, and the RRC reconfiguration message is used to indicate the terminal device (60, 1200) to add the first secondary node, or used to indicate the terminal device to be handed over from a second secondary node to the first secondary node; wherein the RRC reconfiguration message further comprises a first value; and wherein the determining, by the terminal device (60, 1200), or, the chip for the terminal device, based on the indication information, that the key used for signaling transmission performed between the terminal device and the first secondary node by using the second SRB is the first key comprises: when the first value is a preset value, determining, by the terminal device (60, 1200), or, the chip for the terminal device, based on the first value, that the key used for signaling transmission performed between the terminal device and the first secondary node by using the second SRB is the first key.