Abstract: The utilization and function pattern of cultivated land have been profoundly transformed by the socio-economic and historical changes in the urban-rural relationship. The spatiotemporal variation, influencing factors, and spatial spillover of cultivated land multifunction can also greatly contribute to the sustainable utilization of cultivated land resources. However, it is still lacking on the influence of socioeconomic factors on the cultivated land multifunction, particularly with the spatial spillover. Therefore, this study aims to conduct a theoretical analysis of the influencing mechanism of cultivated land multifunction, including the direct and indirect (spillover) effect. Specifically, the direct effects of cultivated land use originated from the labor transfer, the economic level, and agricultural technology. The spillover effects of the cultivated land multifunction were brought about by the spatial proximity, regional competition, and spatial flow of developing elements. Taking Zhejiang Province of China as an example, five functions of cultivated land were selected to calculate the comprehensive index of cultivated land multifunction (MFCI) using the data on cultivated land use, meteorology, soil and socio-economics. Then, the spatiotemporal evolution of MFCI was revealed to determine the driving mechanism of cultivated land multifunction using GIS mapping, spatial autocorrelation, and spatial panel econometric models under the STIRPAT analysis. The results showed that: 1) Most counties in Zhejiang province experienced a trend of rapid decrease, slow decrease, and then a slight increase of cultivated land during 2000-2015. There was an increase in the agricultural production function (APF), net carbon sequestration function (NCF), and landscape aesthetic function of cultivated land (ASF). The water retention function (WRF) remained stable, while the labor carrying function (LCF) decreased gradually in the period. 2) There were strong spillover effects of cultivated land multifunction on the neighboring area. Every 1% increase of MFCI in the local county led to a 0.224% increase in MFCI in the neighboring counties. There were significant positive effects of agricultural labor input, disposable income of rural households, and agricultural machinery level on the MFCI. By contrast, the proportion of secondary industry and urbanization level posed significant negative effects on the MFCI. 3) The industrial structure, agricultural machinery level, and agricultural labor input presented the direct effects on the multifunctional level of cultivated land, whereas, the spillover effects were from the income of urban and rural residents, as well as the urbanization level. Besides, the Kuznets effect was identified in the change of MFCI. A "U" shaped curve with the MFCI was found in the per capita GDP and urban disposable income, whereas, an "inverted-U" shaped curve with MFCI was formed in the disposable income of rural households and agricultural machinery level. Some suggestions were made to strengthen the cooperation in the land consolidation, ecological protection, and agricultural technology, particularly on the spatial interaction within and between counties. Besides, it is necessary to fully understand the specification of resource endowment and the heterogeneity of socio-economic development for the adaptive strategies in cultivated land protection and agricultural support.