A reference signal sending method, comprising: determining, by a first sending device, a first reference signal and a first code resource, wherein the first code resource is orthogonal to a second code resource, the second code resource is used to transmit a second reference signal, the first reference signal is a reference signal of a first type, the second reference signal is a reference signal of a second type, and the first type is different from the second type; sending, by the first sending device, the first reference signal by using the first code resource, wherein the first reference signal is carried on at least one first time-frequency resource group, wherein a value of a quantity of resource elements, REs, occupied by each of the at least one first time-frequency resource group is the same as a value of a length of the first code resource, and the first reference signal and the second reference signal are multiplexed on a time-frequency resource occupied by the at least one first time-frequency resource group, based on the first code resource and the second code resource;, wherein the second reference signal is carried on at least one second time-frequency resource group, wherein a value of a quantity of REs occupied by each of the at least one second time-frequency resource group is the same as a value of a length of the second code resource, the quantity of REs occupied by each of the at least one second time-frequency resource group is the same as or different from the quantity of REs occupied by each of the at least one first time-frequency resource group, and the at least one second time-frequency resource group and the at least one first time-frequency resource group occupy a same time-frequency resource; wherein a reference signal of the first type is of downlink direction and a reference signal of the second type is of uplink direction, or a reference signal of the first type is of uplink direction and a reference signal of the second type is of downlink direction; wherein each of the at least one first time-frequency resource group occupies 2N REs, each of the at least one second time-frequency resource group occupies 2M REs, N is an integer greater than 1, and M is an integer greater than 1. determining, by a first sending device, a first reference signal and a first code resource, wherein the first code resource is orthogonal to a second code resource, the second code resource is used to transmit a second reference signal, the first reference signal is a reference signal of a first type, the second reference signal is a reference signal of a second type, and the first type is different from the second type; sending, by the first sending device, the first reference signal by using the first code resource, wherein the first reference signal is carried on at least one first time-frequency resource group, wherein a value of a quantity of resource elements, REs, occupied by each of the at least one first time-frequency resource group is the same as a value of a length of the first code resource, and the first reference signal and the second reference signal are multiplexed on a time-frequency resource occupied by the at least one first time-frequency resource group, based on the first code resource and the second code resource;, wherein the second reference signal is carried on at least one second time-frequency resource group, wherein a value of a quantity of REs occupied by each of the at least one second time-frequency resource group is the same as a value of a length of the second code resource, the quantity of REs occupied by each of the at least one second time-frequency resource group is the same as or different from the quantity of REs occupied by each of the at least one first time-frequency resource group, and the at least one second time-frequency resource group and the at least one first time-frequency resource group occupy a same time-frequency resource; wherein a reference signal of the first type is of downlink direction and a reference signal of the second type is of uplink direction, or a reference signal of the first type is of uplink direction and a reference signal of the second type is of downlink direction; wherein each of the at least one first time-frequency resource group occupies 2N REs, each of the at least one second time-frequency resource group occupies 2M REs, N is an integer greater than 1, and M is an integer greater than 1.