Abstract: Based on the perspective of planting production, exploring the impact of rural population aging on the use of agricultural machinery has certain practical significance for the current sustainable development of agriculture in China. Firstly, the Malmquist index method was used to calculate the total factor productivity of planting industry in 30 provinces and cities in China from 2004 to 2018, and further calculated the comprehensive development level of agricultural mechanization in various regions. Secondly, using the panel threshold model and taking the aging degree of rural population as the threshold variable, this paper studied the nonlinear relationship between agricultural mechanization and total factor productivity of planting industry. Finally, by introducing the instrumental variable terrain, this paper explored the endogenous problem between agricultural mechanization and total factor productivity of planting industry. The results showed that there was a single threshold effect between agricultural mechanization and total factor productivity of planting industry. Under the high aging level in rural areas, it was not conducive to the improvement of total factor productivity of planting industry by agricultural machinery. When the aging rate of rural population was lower than 13.45%, the total factor productivity of planting industry will increase by 0.000 4 for every unit of comprehensive development level of agricultural mechanization. When the aging rate was higher than 13.45%, the total factor productivity of planting industry will decrease by 0.002 for every unit of comprehensive development level of agricultural mechanization. Topography will affect the level of agricultural mechanization, and then affect the total factor productivity of planting industry.