In view of the performance decline caused by spectrum mismatch in transform domain communication system, a basic function generation algorithm based on joint channel status coding is proposed in this paper. The algorithm is used to conduct quarternary synthetic coding on the channel status of both transmitter and receiver, divide the joint channel into four states, choose good frequency points for data transmission according to the mismatch rate, and then implement filtering on the received signal before demodulation. Theoretical analysis implies that, in the same situation, the spectrum utilization rate of the joint channel status coding is higher than that of spectrum exchange mechanism, thus avoiding the transmitter and receiver to give up communication further close to the real situation. The simulation results show that the antiinterference performance of the algorithm is superior to that of spectrum exchange mechanism, and can effectively improve the spectrum utilization of the system, and reduce the impact of spectrum mismatch on interference performance, and expand the scope of application of TDCS.