The effects of ecological restoration based on ecosystem services (ES) have attracted more and more attention, while the simulation and cost–benefit analysis of ecological restoration scenarios are not well investigated. In this study, four ecological restoration scenarios were simulated at a typical watershed on the Qinghai-Tibetan Plateau (QTP) based on the land use conversion. Scenario 1 was only grassland restoration, Scenario 2 and 3 were mainly farmland to shrub, and Scenario 4 was mainly grassland restoration with bare land converting to forest and shrub. The ecosystem services value (ESV) and the cost-benefits of these scenarios were quantified and compared in 25 years after the restoration investment. The results showed there were significant differences in the ESV under four scenarios, among which Scenario 4 had the largest ESV and Scenario 1 had the smallest ESV. The spatial distribution of ESV was uneven, and high-value regions were concentrated in the southwest and central regions. There were great variations between original scenario and simulated scenarios, but a little difference between Scenarios 2, 3, and 4. The largest loss of farmland abandonment was regulating service, followed by supporting service, provisioning service, and cultural service. From the perspective of payback period, Scenario 1 was the fastest, and it could obtain net benefits first. From the short- and long-term (6 and 25 years after investment) benefits, Scenarios 1 and 4 had the largest cumulative ESV increase, respectively. The results of this study can provide a basis for the formulation and implementation of ecological policies.