Aiming at MIMO-OFDM wireless communication system, we propose a simple and effective space-frequency coding algorithm: time-domain cycle delay algorithm, which implements space-frequency coding using the cycle delay of OFDM time-domain signal. The academic analysis and computer simulations indicate that this kind of space-frequency coding algorithm not only can achieve full diversity gain but also has such advantages as: the algorithm is independent of the number of transmit antennas; the calculation amount of the algorithm is little and it is easy to implement the algorithm.