The purpose of this paper is to explore the relationship between part-time farming and the nutrition and health of rural residents, test the possible effects through two potential pathways—income effect and time effect—and further analyze the family heterogeneity characteristic of downward intergenerational support. Using the ordered probit model and cross-sectional data from the China Rural Revitalization Comprehensive Survey (CRRS), which provide information on household income, health conditions, and nutritional caloric intake, this study estimates the relationship between part-time farming and the nutritional health of rural residents. The effects are decomposed into income (measured by dietary diversity scores and food consumption expenditures) and time effects (measured by excess caloric intake), with additional analysis on family heterogeneity concerning downward intergenerational support. Part-time farming positively correlates with rural residents’ nutritional health through two pathways: income effect (improved dietary diversity and increased food consumption) and time effect (negative impact of excessive caloric intake). Downward intergenerational support mitigates the negative time effect. This paper highlights the often-overlooked impact of part-time farming on rural nutrition and health, emphasizing non-linear effects and the significant role of downward intergenerational support, thus filling a gap in existing research.