Experiment on effects of Si, Ca, K fertilizer applications on dried Radix rehmanniae was done. The result showed that among seven treatments, output of dried Radix rehmanniae was highest as the amount of Si, Ca, K fertilizer application was 1500kg per hectare and the fresh output and dry one increased by more 22.44% and 40.57% than one of CK; and that the profit was the best as the amount of Si, Ca, K fertilizer application was 750 kg per hectare and input/output was in turn 6.53 and 18.81 as fresh and dry. The suitable amount of Si, Ca, K fertilizer application thongh regression was 2086.95kg(per hectare) with 24.79 ton fresh output and 2062.2kg with 6.53 ton dry output.