A polar code hybrid automatic repeat request method, wherein the method comprises: obtaining, by a communications device, a bit sequence of retransmission information, wherein the bit sequence of the retransmission information comprises K retransmission information bits determined from a bit sequence of first transmission information, the bit sequence of the first transmission information comprises N first transmission information bits, N is a positive integer, and K is a positive integer not greater than N; performing, by the communications device, polar code encoding on the bit sequence of the retransmission information, to obtain an encoded retransmission bit sequence; and sending, by the communications device, the encoded retransmission bit sequence to another communications device; wherein the K retransmission information bits in the bit sequence of the retransmission information are arranged according to a preset order or an order reverse to the preset order, and the preset order is the same as an arrangement order of the N bits in the bit sequence of the first transmission information; or the bit sequence of the retransmission information comprises I sequentially arranged groups, wherein retransmission information bits comprised in each of the I groups are arranged according to a preset order or arranged according to an order reverse to the preset order, the preset order is the same as an arrangement order of the N bits in the bit sequence of the first transmission information, and I is a positive integer not greater than K; wherein the K retransmission information bits are K bits having lowest reliability among the N first transmission information bits. obtaining, by a communications device, a bit sequence of retransmission information, wherein the bit sequence of the retransmission information comprises K retransmission information bits determined from a bit sequence of first transmission information, the bit sequence of the first transmission information comprises N first transmission information bits, N is a positive integer, and K is a positive integer not greater than N; performing, by the communications device, polar code encoding on the bit sequence of the retransmission information, to obtain an encoded retransmission bit sequence; and sending, by the communications device, the encoded retransmission bit sequence to another communications device; wherein the K retransmission information bits in the bit sequence of the retransmission information are arranged according to a preset order or an order reverse to the preset order, and the preset order is the same as an arrangement order of the N bits in the bit sequence of the first transmission information; or the bit sequence of the retransmission information comprises I sequentially arranged groups, wherein retransmission information bits comprised in each of the I groups are arranged according to a preset order or arranged according to an order reverse to the preset order, the preset order is the same as an arrangement order of the N bits in the bit sequence of the first transmission information, and I is a positive integer not greater than K; wherein the K retransmission information bits are K bits having lowest reliability among the N first transmission information bits.