A transport block retransmission method and a base station are described. In the method, for first m retransmissions of a transmission block (TB), a closed-loop spatial multiplexing transmit manner for initial transmission of the TB is maintained. The method may also include, for last N-m retransmissions of the TB, a transmit manner is changed into an open-loop transmit manner when a transmission mode remains unchanged. Retransmission of the TB in the open-loop transmit manner can improve reliability of data transmission, reduce a quantity of retransmissions of the TB, reduce a residual block error rate and a voice packet loss rate, and ensure that a closed-loop gain can be effectively obtained.