Heilongjiang reclamation area has become one of the major commodity grain bases in China, in the context of spatial distribution pattern shifted from "grain supply from north to south" to "grain supply from south to north" in the country. Therefore, it is essential to stabilize grain output and make it sustainable in this base so as to ensure Chinese food security, and research on impact factors of grain yield is among the focuses for the agricultural policy. Twenty-three factors, which are most closely related with agricultural production, are selected from 113 farms in the area, and be imported into Geographical Detector to analyze different influences of them on the grain out. These factors include population density, cultivated area, year-end population, employment in primary industry, total investment in agriculture, payment to employed persons, total savings deposit, net per capita income, classified highway, number of home computers, total power of farm machinery, machinery tilled land area each year, machinery sown area each year, effective irrigation area, fertilizer input, electricity used in agriculture, grain storage, the number of grain processing center, the processing speed of grain processing center, crops acreage sown, annual average temperature, annual average precipitation, and hours of sunshine. Results showed that the six most important impact factors were sown area, cultivated area, machinery tilled land area each year, machinery sown area each year, consumption of chemical fertilizers, and total power of farm machinery. As agricultural machinery level played an important role in grain production of farms in the area, influences of 15 different agricultural machines are furtherly analyzed, which indicated that the five most important ones were combined harvesters, complementary mechanization to large and medium agricultural tractors, self-driven combine, large and medium agricultural tractors, and self-driven rice planter. So there is a significant demand for increasing investment in agricultural technological research, and mechanization, and developing precision agriculture in the area.