The invention provides a decoding method for low-density check code of multi-input multi-output orthogonal frequency division multiplexing system. On the basis of the log-likelihood ratio belief propagation principle, the method is characterized in that log-likelihood ratio belief propagation decoding of the low-density check code is realized by a coordinate rotation digital computer structure, ashifter, and correlated operation of an adder, a multiplier and a divider. The decoding method further realizes multiplexing of the coordinate rotation digital computer structure by a selector so that the decoding structure of the low-density check code is simpler.