The embodiment of the invention provides an information transmission method, a sending terminal device and a receiving terminal device. The information transmission method comprises the following steps: confirming the mother code length N of a Polar code according to the load of a first channel, wherein the load of the first channel is N bits, the N is 2<n>, and the n is a positive integer; performing Polar code coding on the target information to be transmitted to obtain N coded bits; and transmitting the N coded bits through the first channel. In the embodiment of the invention, the number of coded bits obtained after the Polar code coding is equal to the load length of the channel, therefore, the N coded bits is not required to perform a rate matching process when transmitted through the first channel, and the coding overhead of the channel is simplified; and because the rate matching is not required, the complexity and delay of the channel coding are greatly reduced, and the performance loss caused by the rate matching operation is avoided.