Abstract: The black soil region in Northeast China is a major grain-producing area in China. To ensure the sustainable development of agriculture in the black soil region, the data from the third national land resource survey, remote sensing data, and the digital elevation model (DEM) can be integrated to explore the ecological protection assessment methods for cultivated land. This study investigated Nenjiang City, Heilongjiang Province, from the location conditions of cultivated land and surrounding ecological land use. It constructed five indicators, including the forest health index, the proportion of ecological land surrounding cultivated land, the distance to the nearest forest, the slope, and the topographic position. Notably, an improved forest health index was designed based on the remote sensing ecological index to comprehensively assess the ecological protection of cultivated land in Nenjiang City. The results indicate that the cultivated land in Nenjiang City was dominated by medium-low and medium ecological protection grades, covering 34.21% and 45.28% of the cultivated land area, respectively. In contrast, the high-grade cultivated land accounted for merely 2.11%, indicating considerable potential for improving the ecological protection grade of cultivated land. Among individual indicators, the proportion of ecological land around cultivated land and the forest health index exhibited low values, serving as the primary factors leading to an overall slightly low geological protection grade in the study area.