The inherent contradiction between grain production service and soil conservation service poses a substantial impediment to the sustainable development of the Nu River Basin. Grain production service has a direct impact on the livelihoods of local farmers, serving as the primary source of income for farming households. Meanwhie, soil conservation, as a vital regulatory service, plays a crucial role in preventing regional land degradation. However, there is currently a scarcity of case studies investigating the relationship between grain production service and soil conservation service in the Nu River Basin. Taking Shidian County at the center of the basin as an example, this study used the Mean Square Error (RMSE) method to assess the spatial characteristics of the trade-off intensity between grain production and soil conservation services from 2000 to 2020. Taking the year 2020 as a pivotal baseline and slope farmland ecological restoration as the decision variable, a sophisticated multi-objective linear programming approach was subsequently applied to identify priority restoration areas. This comprehensive analysis revealed the spatial variations of trade-off intensity and ecological restoration potential. The results showed that: 1) There were significant spatial differentiation in the trade-off of ecosystem services, with an increasing trend of trade-off intensity over the study period. The average RMSE exhibited an increase from 0.466 to 0.499 during 2000-2020, signaling the imperative for strategic interventions. High trade-off intensity areas were mainly concentrated in the low-altitude regions, while low trade-off intensity areas were scattered. Both high and low trade-off intensity areas exhibited clustering features in spatial distribution. 2) Moreover, according to the efficiency frontier curve derived from linear programming, to achieve soil conservation service benefit of 13.35×10⁶ t hm^-2 a^-1, 3388.51 hm² of slope farmland needed to be converted. This conversion, however, resulted in the loss of 9.59×10⁶ kg grain production services. Further improvement in soil conservation service would incur significantly higher costs, highlighting the delicate balance required for effective land management. 3) The ecological restoration potential of slope farmland varied among trade-off intensity levels, with medium trade-off intensity > low trade-off intensity > high trade-off intensity. Specifically, slope farmland with trade-off intensity range of 0.4-0.5 emerged as the most suitable for ecological restoration efforts. For slope farmland with other trade-off intensity levels, it is advisable to implement soil conservation measures to regulate. These research findings offer valuable insights into the utilization of slope farmland in mountainous regions, providing scientific guidance for sustainable land management practices, thereby contributing to the achievement of sustainable development goals.