The invention discloses a self-adapting modulating and coding method in orthogonal frequency division multiplexing system, it includes: the first step, setting original time window; the second step, obtaining adapted time window based on time window parameter; the third step, based station evaluates average RSSI value and standard difference of down sending time window; the forth step, inquiring AMC judging graph to obtain corresponding modulating and coding mode based on average RSSI value and standard difference; the fifth step, evaluating error code ratio, and comparing with expected errorcode ratio: if evaluated error code ratio <= expected error code ratio, turn to step six; If else, adjust time window parameter, turn to step two; the sixth step, modulate and code. The invention canobtain modulating and coding mode which fits for current channel, increases actual effect of AMC, decreases possibility of interrupt of system, increases spectrum efficiency, at the same time error ratio can be decreased.