The cooperative transmission is an efficient way in the wireless network which benefits from the spacial diversity. In this paper, we introduce and analyze a novel three-node relay protocol with high transmit efficiency, termed as the Adaptive Cooperative Coding (ACC). This technique is implemented by transmitting the rate-compatible punctured convolutional code (RCPC code) sequence and its complementary punctured convolutional (CPC) sequence during the two-hop transmission. Compared with the conventional cooperative transmission, the ACC scheme remarkably improves the achievable data rate and is adjustable to variable channel conditions. Furthermore, we deduce the theoretical upper bound of the ACC protocol, from which the lowest packet error probability can be achieved by selecting a proper coding rate for the first hop.