Abstract: LDPC layered decoding algorithm can effectively reduce the hardware complexity and significantly reduce the decoding iterations, which has been widely used in the LDPC decoder design. In order to improve decoder performance, check nodes updated in order according to the reliability in this algorithm. Meanwhile, the sum of the absolute value of information nodes log likelihood ratio minimum and second minimum is used to judge the reliability. Based on china mobile multimedia broadcasting standard 1/2 code rate LDPC codes, we simulate and compare the conventional layered decoding algorithm with the improved layered decoding algorithm. The result shows that:under the same bit error rate, the performance of the improved algorithm improves nearly 0.4dB and convergence speed speeds up obviously.