Improving farmers' income in Southwest China involves analyzing how rural investment and agricultural land use efficiency affect it. The study found that factors like the size and efficiency of agricultural land, as well as the level of rural investment, have a positive impact on farmers' income in the long term. Agricultural land size has a greater influence on income growth than rural investment. In the short term, increasing rural investment can help boost farmers' income, but improving agricultural land efficiency may initially reduce income growth. Increasing the size of agricultural land can also lead to higher farmer income within a certain range.