The non-rule circulates LDPC code is the core of the forward-acting error correction code of our country digital television broadcasts in ground DTMB transmission standard. In view of sub block characteristic of this LDPC code generates matrix. It has designed a kind of LDPC encoder based on the linear feedback shift register structure to achieve the LDPC real-time encoding under three different code rates. The whole design occupies 4699 ALUTs, it shorten 20% logical resources compared with same designable project. It fits low complexity DTMB standard transmitter to develop.