An orthogonal network space-time coding method, which is used in a wireless communication network comprising a target node, a source node (S 1; S Ns) and a relay node, comprising: Step A, the source node (S 1; S Ns) broadcasting data information to the relay node and the target node, the Step A requiring T SR symbol periods; and Step B, the relay node performing, after receiving the data information transmitted by the source node, orthogonal network space-time coding, and transmitting the coding data to the target node, with Step B requiring 2 symbol periods, characterized in that Step B comprises a process of relay node decoding, a process of estimation information grouping, a process of estimation information compression, a process of compressed data space-time coding and a process of space-time transmission, wherein the process of relay node decoding is: the relay node performs maximum likelihood decoding, according to the received signal, to obtain estimation information of signal vectors transmitted by N S source nodes (S 1; S Ns), the number of which is corresponding to the number N S of the source nodes; the process of estimation information grouping is: a relay node R divides the estimation information of the signal vectors transmitted by all the N S source nodes from the 0 th symbol period to the T SR - 1 th symbol period, into two T SR N S 2 × 1 -dimensional column vectors; the process of estimation information compression is: the two T SR N S 2 × 1 -dimensional column vectors obtained in the process of estimation information grouping are respectively compressed into two complex signals x R 1 and x R 2; the process of compressed data space-time coding is: the two complex signals x R 1 and x R 2 obtained in the process of estimation information compression constitute a 2×2 matrix; and the process of space-time transmission is: the 2×2 matrix is transmitted respectively by two antennas of the relay node, within two symbol periods. Step A, the source node (S 1; S Ns) broadcasting data information to the relay node and the target node, the Step A requiring T SR symbol periods; and Step B, the relay node performing, after receiving the data information transmitted by the source node, orthogonal network space-time coding, and transmitting the coding data to the target node, with Step B requiring 2 symbol periods, the process of relay node decoding is: the relay node performs maximum likelihood decoding, according to the received signal, to obtain estimation information of signal vectors transmitted by N S source nodes (S 1; S Ns), the number of which is corresponding to the number N S of the source nodes; the process of estimation information grouping is: a relay node R divides the estimation information of the signal vectors transmitted by all the N S source nodes from the 0 th symbol period to the T SR - 1 th symbol period, into two T SR N S 2 × 1 -dimensional column vectors; the process of estimation information compression is: the two T SR N S 2 × 1 -dimensional column vectors obtained in the process of estimation information grouping are respectively compressed into two complex signals x R 1 and x R 2; the process of compressed data space-time coding is: the two complex signals x R 1 and x R 2 obtained in the process of estimation information compression constitute a 2×2 matrix; and the process of space-time transmission is: the 2×2 matrix is transmitted respectively by two antennas of the relay node, within two symbol periods.