Leakage power is growing comparable to dynamic power dissipation as a result of technology trends, and thus it has become an important issue in low-power circuit design. As a popular technique for standby power reduction, power gating is applied to high-parallel LDPC decoder for WiMAX standard. The clustered-block processing engine (CBPE) array are divided into 9 power domains, and they are switched on or off according to different code lengths of LDPC code defined in WiMAX standard. As CBPE array occupies about 70% of the decoder system, the dedicated power gating strategy is very effective in shorter code length case since more power domains can be switched off. At shortest code length, power gating design brings about 55% power reduction compared to that of longest code length.