A retransmission method for a time division duplexing self-adaptive frame structure, and a network side device relate to a technology of dynamically allocating uplink and downlink sub-frames in an LTE-advance (3GPP Release11) TDD communication system. The method comprises: during transmission of a TDD self-adaptive frame, for an uplink sub-frame, if a frame structure, of which an RTT period of PHICH and PUSCH of the uplink sub-frame is 10 ms, corresponding to the uplink sub frame is found in 7 types of defined frame structures, then sending PHICH data on a corresponding downlink sub-frame in the found frame structure, and sending retransmission data on the corresponding uplink sub-frame in the found frame structure. The solution ensures HARQ compatibility of an uplink data channel of R10UE. In addition, A/N feedback of the PDSCH is configured according to the uplink A/N resolution, thereby improving retransmission performance.