Abstract: Scientific measurement and spatial difference analysis of the development level of agricultural mechanization in different regions of Shanxi Province is of great significance to promote the overall coordinated and rapid development of agricultural mechanization in Shanxi Province. The weighted synthesis method and the improved polygon area method were used to calculate the comprehensive mechanization rate of Shanxi Province and its 11 prefecture-level cities from 2017 to 2019. The cluster analysis method was used to classify prefecture-level cities. The Theil index was used to analyze the differences of mechanization development levels in different regions, and the ArcGIS software was used to display their spatial distribution intuitively. The results showed that the weighted method was generally higher than the polygon area method. In 2019, the comprehensive mechanization rate of Shanxi Province reached 58.78%, among which the comprehensive mechanization rate of Yuncheng, Shuozhou, Jinzhong, and Linfen exceeded that of the whole province. During the studied period, the average mechanization degree of the five links of ploughing, sowing, irrigation, plant protection, and harvest in the province were 75.48%, 73.64%, 64.49%, 24.80%, and 53.23%, respectively, showing an obvious imbalance. The weakest link restricting the development of agricultural mechanization was plant protection. According to the level of agricultural mechanization, prefecture-level cities could be divided into three types of regions. The overall difference in agricultural mechanization level in the whole province showed a slight fluctuation. The difference between regions is always greater than the difference within regions, and its average contribution rate to the overall difference was as high as 73.37%. To balance the development of agricultural machinery in various cities of Shanxi Province, we should focus on narrowing the development differences between regions. It was concluded that the factors of natural environmental conditions, the imbalance of social and economic development, local agricultural policies, and farmers’ attention were the main reasons for this difference.