In conventional LDPC decoders, the real-time processing performance should meet its maximum decoding iterations for all packets and the work frequency or supply voltage is always fixed at a high level, which decreases its energy efficiency. In this paper, an energy-efficient LDPC decoding architecture with an adaptive voltage-frequency scaling (AVFS) scheme is presented. According to the usage of input packet FIFO related to variable decoding iterations，the architecture dynamically adjusts its work frequency and supply voltage to reduce the processing energy while meeting its real-time processing requirement. Finally, the decoder is implemented with 28nm CMOS process. Experimental results show that our decoder has a throughput of 1590Mb/s when the raw bit error rate (RBER) of Flash memory is up to 10-2. The power consumption of the decoder can be reduced by 25%-62% and energy efficiency can be increased to 1.3-2.5 times under different AWGN noise.