A method applied for a terminal device (60, 121) and for sidelink transmission, comprising: obtaining a transmission requirement of first data, wherein the first data needs to be transmitted on a sidelink; and when a first resource does not meet the transmission requirement of the first data, sending request information to a network device, wherein the request information is used to request to configure a second resource, the first resource is a resource that is configured by using a broadcast message and that is used to transmit data on the sidelink, and the second resource is a resource that is configured by using a unicast message and that is used to transmit data on the sidelink, wherein the obtaining the transmission requirement of the first data comprises: receiving configuration information from the network device, wherein the configuration information is used to configure a correspondence between a service type of data and a channel busy ratio, CBR, threshold; and determining, based on the correspondence and a service type of the first data, a CBR threshold corresponding to the first data, wherein the CBR threshold corresponding to the first data is the transmission requirement of the first data; the method further comprises: when a CBR of the first resource does not meet the CBR threshold corresponding to the first data, determining that the first resource does not meet the transmission requirement of the first data, and wherein sending request information to the network device comprises: requesting, in a random access process by using a message 3, the network device to configure the second resource, wherein the message 3 carries the request information and the message 3 further carries a CBR corresponding to a carrier or a frequency of the second resource, so that the network device is enabled to configure the second resource. obtaining a transmission requirement of first data, wherein the first data needs to be transmitted on a sidelink; and when a first resource does not meet the transmission requirement of the first data, sending request information to a network device, wherein the request information is used to request to configure a second resource, the first resource is a resource that is configured by using a broadcast message and that is used to transmit data on the sidelink, and the second resource is a resource that is configured by using a unicast message and that is used to transmit data on the sidelink, wherein the obtaining the transmission requirement of the first data comprises: receiving configuration information from the network device, wherein the configuration information is used to configure a correspondence between a service type of data and a channel busy ratio, CBR, threshold; and determining, based on the correspondence and a service type of the first data, a CBR threshold corresponding to the first data, wherein the CBR threshold corresponding to the first data is the transmission requirement of the first data; receiving configuration information from the network device, wherein the configuration information is used to configure a correspondence between a service type of data and a channel busy ratio, CBR, threshold; and determining, based on the correspondence and a service type of the first data, a CBR threshold corresponding to the first data, wherein the CBR threshold corresponding to the first data is the transmission requirement of the first data; the method further comprises: when a CBR of the first resource does not meet the CBR threshold corresponding to the first data, determining that the first resource does not meet the transmission requirement of the first data, and wherein sending request information to the network device comprises: requesting, in a random access process by using a message 3, the network device to configure the second resource, wherein the message 3 carries the request information and the message 3 further carries a CBR corresponding to a carrier or a frequency of the second resource, so that the network device is enabled to configure the second resource. requesting, in a random access process by using a message 3, the network device to configure the second resource, wherein the message 3 carries the request information and the message 3 further carries a CBR corresponding to a carrier or a frequency of the second resource, so that the network device is enabled to configure the second resource.