In this paper, we consider the uplink of a coded MIMO-OFDM multiuser system with transmitting precoding in frequency-selective fading channels, where the transmitters (user) as well as the receiver (base station) are equipped with multiple antennas. Each user's information bit sequence is independently encoded by a turbo encoder, spatial multiplexed and then spread by orthogonal Walsh code (OWC), interleaved, linear precoded, OFDM modulated and transmitted through its transmit antennas. At the receiver, we combine interference cancellation (IC) detection of multiple antennas and multiuser and turbo decoding to form a system iterative feedback structure, which jointly optimizes and improves the performance of detection and decoding. In this paper, we also consider a scheme for transmitting linear precoding to balance the complexity of transmitter and receiver and help to improve the ability of IC detection. Through computer simulation results, we verify the system performance in frequency-selective fading channels.