Promoting farmers’ adoption of agricultural technologies that can improve the quality of cultivated land is important for the construction of high standard farmland. At present, credit demand rationing may cause the lack of capital investment of farming households in China. This study used the survey data of 957 grain growers in four provinces of China to examine whether credit demand rationing affects farmers’ adoption of technologies that improve cultivated land quality. A conditional mixed-process model was used for the analysis and the moderating effect of farmer differentiation on the impact of credit demand rationing on agricultural technology adoption was explored. The results show that: (1) At present, the adoption rate of agricultural technologies that improve cultivated land quality is low, and credit demand rationing is widespread. It is particularly high in the central and western parts of China, but low in the east; (2) Credit demand rationing has a negative impact on the adoption of agricultural technologies that improve cultivated land quality with the demand of capital investment, but has no significant impact on the technologies without the demand of capital investment; (3) Farmer differentiation has moderating effects on the impact of credit demand rationing. That is, under the background of credit demand suppression, there are significant differences between different types of farmers in the use of agricultural technologies with short-term benefits, and no significant difference in the use of agricultural technologies with long-term benefits.