This　paper　propose　multichannel　random　demodulator　(MCRD)　system,　which　is　block　structured　sparsity　based　of　multiband　signals.　It　is　a　kind　of　compressive　sampling　system.　Each　channel　of　the　system　firstly　multiplies　analog　signal　by　a　band　of　random　sequence,　the　product　is　put　into　integrator　and　sampled　at　a　low　rate.　ADC　of　this　system　only　need　to　generate　one　sample　which　greatly　reduce　ADC　design　complexity.　Perfect　recovery　from　the　proposed　samples　is　achieved　by　processing　all　measurements　jointly　with　orthogonal　matching　pursuit　(OMP)　algorithm.　The　simulation　analyzes　the　compression　rate,　the　number　of　effective　sub-carriers　and　conversion　rate　of　pseudorandom　number　generator　impact　on　this　system.　The　results　show　that　MCRD　system　ensure　perfect　reconstruction　performance　for　multiband　signal　that　is　sampled　below　the　Nyquist　rate.　Specially,　conversion　rate　impact　on　system　performance　would　be　greatly　for　higher　sampling　rate,　select　the　appropriate　conversion　rates　can　improve　the　system　performac-e　while　reducing　system　complexity.　©　2013　IEEE.