Abstract: Twenty-eight Père David's deer (Elaphurus davidanus) in Da-feng Milu Reserve were immobilized with a new anaesthetic compound Miannaining (MNN) and antagonized by Suxingling No.4 (SXL-4). There was a significant difference in mean walk time between unexcited deer (5.03±1.99min) and excited ones (1.68±0.19 min).Some deer become recumbent again after antagonism, but no apparent adverse effects were found. We established a formula (DSI=(C-Dr)/-Dt) to compare the sensitive of Père David's deer to MNN between sex and ages. And formulated the following dosages of MNN for Père David's deer: excited adult males 0.8~1.0 ml/100 kg; adult females 1.2~1.4 ml/100 kg; juveniles 1.0-1.2ml/100kg, unexcited adult males 0.5~0.7ml/100 kg; adult females 0.6~0.8 ml/100 kg; juveniles 0.6~0.8 ml/100 kg. SXL-4 is giving intravenously at a dosage 1.5~2.0 times of MNN.