Abstract: A low-complexity early stopping criterion has been developed by directly observing the number of non-zeros in the check matrix during each iteration of LDPC decoder. Instead of a great number of complex computations, the new approach needs only a few simple operations. Simulation results of 800×9 216 LDPC codes in CMMB system proved that the proposed approach could greatly reduce the average iteration numbers with only a few performance degradations. Compared with the classic criterions, the proposed criterion has low complexity, little performance degradation and only little hardware consumption.