Abstract Wild sika deer (Cervus nippon) are threatened by habitat loss and fragmentation throughout East China. Using 18-year demographic data, we conducted a viability analysis to predict the fate of a wild sika deer population threatened by loss of suitable habitat in the Taohongling National Nature Reserve, Southeast China. We simulated performance of proposed management interventions — population recruitment and habitat restoration — in preventing the sika deer population from declining. In the scenario where 60% or 30% of suitable habitat was lost, the population viability model predicted 99.6% and 85.5% probability of population decline by 40 years, respectively. The modelling demonstrated that carrying capacity, which was affected by vegetation succession and socioeconomic development, would restrict the growth of the sika deer population. The survival rate of adults is the element most affecting population growth, yet supplementation of adult deer was predicted to be less effective than habitat restoration in reducing risk of population decline in all habitat scenarios. Large-area but less-intensive restoration should be considered at initial stage of the intervention if the funding was sufficient to support. Regarding these findings, we recommend future management interventions to target towards increasing suitable habitat as well as preventing habitat loss and fragmentation in Taohongling National Nature Reserve. The zoning scheme and its management need to be regulated with conservation incentives.