Farmland ecosystems can provide agricultural products to perform various ecological regulation functions. However, these intangible services are often overlooked during evaluation. This study aims to quantitatively assess the farmland ecosystem services in China from 1992 to 2022. Their spatiotemporal evolution and driving factors were clarified to promote sustainable farmland use and agricultural green transformation. An evaluation framework was then constructed to cover five positive services—supply, regulation, support, culture, and social security (15 secondary indicators)-and one negative service related to environmental pollution (4 secondary indicators). The ecosystem services were quantified using ecological economics. Finally, 15 indicators were selected from four dimensions-economic, social, natural, and technological—to identify the driving factors on the spatial differentiation of farmland ecosystem service, according to the grey relational analysis. The results show that: 1) The total service value increased from 5 098.12 billion yuan in 1992 to 11 312.14 billion yuan in 2022, with an average annual growth of 207.13 billion yuan. The value per unit area increased by 66%. Among the positive services, supply services accounted for the highest proportion (48.1%-66.8%), while regulation and support services accounted for 18.6%-25.4% and 10.5%-16.5%, respectively. The value of negative services showed an initial increase followed by a decrease, peaking in 2012 and declining by 6.4% in 2022, compared with 2012. 2) The total service value in the Central-Southern and Eastern China regions accounted for over 50% of the national total, with the value per unit area significantly higher than in the rest of the regions. The Northwest region contributed less than 10% of the total, while the Northeast region had the lowest increase in value per unit area. At the provincial level, 11 provinces, including Henan and Shandong, collectively accounted for two-thirds of the national total value. Beijing and Shanghai experienced a decline in value, due to reduced farmland areas, while Xinjiang recorded the highest increase (357.9%), owing to farmland expansion. 3) Technological factors (relational degree 0.802) had the strongest influence, followed by social (0.671) and economic factors (0.667), while natural factors had the least impact (0.592). Among the secondary indicators, the main driving factors were agricultural labor input, mechanical power level, irrigation level, electricity usage, and financial support for agriculture (all with relational degrees > 0.7). In conclusion, the value of farmland ecosystem services increased, but there were significant regional disparities, with the dominant roles of technological, socio-economic, and policy factors. Future efforts should focus on agricultural technology and financial support policies for the positive service value of farmland ecosystems in sustainable agriculture.