For selection of medicinal plant extracts to be applied into citrus postharvest preservation, the inhibition effect of Macleaya cordata and Polygonum cuspidatum on Penicillium digitatum and its preservation effect during citrus storage were studied. The results were as follows: Both M. cordata and P. cuspidatum could inhibit growth of P. digitatum, ED50 of which were 184.32 and 538.48 mg/L respectively, especially the inhibition effect of M. cordata was better. With comparison of water treatment, the two kinds of medicinal plant extracts could both effectively prevent Bingtangcheng from decay. With comparison of conventional chemical preservative, the decay rates of Bingtangcheng respectively treated by the two kinds of medicinal plant extracts had no statistical significance, but Ponkan significantly increased. The water losing rates of Bingtangcheng respectively treated by the two kinds of medicinal plant extracts were no statistical significance compared with conventional chemical preservative, but the water losing rates of these three treatments were significantly lower than water treatment. The effects of the two kinds of medicinal plant extracts on decay and fresh-keeping of Bingtangcheng were similar to conventional chemical preservative.