This research analyzed the spatial pattern, crop structure and contributing factors of yield increase in 13 major grain producing provinces in China, so as to provide a decision-making basis for maintaining the growth trend, optimizing grain production layout, adjusting planting structure and realizing steady grain yield increase in China’s major grain producing areas. Using LMDI model and GIS spatial analysis method, the total grain yield in the main producing areas was divided into two factors: sowing area and crop yield per unit area, and the yield increase pattern and contributing factors were analyzed. From the spatial distribution of grain yield increase in the main producing areas: the main producing areas in north China are better than those in the south, and the center of gravity of grain yield increase shows an obvious northward trend. In terms of yield increase structure, maize is the main contributing variety, followed by wheat, and the contribution rate of rice is the lowest. From the contributing factors of grain yield increase in main producing areas, the contribution rate of per unit area yield is higher than that of sowing area, and the spatial difference is obvious. In terms of crops, the sowing area effect of rice and maize is positive, the effect of maize is greater than that of rice, and the sowing area effect of wheat has a negative impact. The per unit area yield effect of the three crops is positive, and that of wheat is the most significant, while the order is wheat > rice >maize. The increase of both the planting area and the per unit area yield contribute positively to the increase of grain yield in the main producing areas. For areas that mainly rely on the increase of sowing area to raise the yield, we should adjust the planting structure, carry out reasonably rotation, excavate advantageous crops, increase the popularization of agricultural technology and improve the land output. For areas with significant contribution from per unit area yield, it is necessary to develop characteristic industrial advantage areas, form cluster development, provide all-round services in production, circulation and sales, and prevent the phenomenon of higher production not accompanied by higher income.