A decoding method for low density generator matrix codes is disclosed, which decodes a bit information sequence that is transmitted after encoding with LDGC, the method comprises: S1: filling L−K known bits in a received code word sequence R and deleting code word symbols erased by a channel in R, and getting Re; S2: deleting rows corresponding to the code word symbols erased by a channel from a transposed matrix Gldgct of an LDGC generator matrix, and getting Ge; S3: obtaining It according to relation Ge×It=Re; S4: obtaining st according to relation Gldgct(0:L−1,0:L−1)×It=st, and getting an original information sequence of K bits by deleting the filled L−K known bits from st. The present disclosure can significantly reduce the storage overhead of a decoder, accelerate the decoding speed, and allow LDGC to be more smartly used in high speed communication systems.