Based on the data of 3251 rural households in China, this paper compares the effects of different harvesting ways and social services (purchase of agricultural machinery services) on the loss of harvesting links of wheat, rice and maize. The results showed that compared with manual harvesting, the whole mechanized harvesting generally increased grain losses of the harvesting link, and in terms of varieties, increased rice losses, but it reduced wheat losses, and the semi-mechanized harvesting significantly reduced corn losses. In-depth study found that the purchase of agricultural machinery services can significantly reduce wheat losses in harvesting link. The results of robustness test are consistent. Based on this, this paper believes that, for wheat, we should promote the whole process of mechanization, while for rice and corn, we must develop small-scale and professional agricultural machinery suitable for farmers, so as to advance the mechanization of segments in the short term.