Abstract: In recent years, China has imported a large amount of grains from international market, which may threaten the national food security. It is of great significance for the national food security to investigate the international competitiveness of China's grain industry. Taking the United States (US) as the comparative study object, with the help of costs-returns data of Chinese and American agricultural products, this paper discusses the international competitiveness of China's grain industry from three aspects: land productivity, production cost and sales price. The results show that: 1) From 1998 to 2016, the land productivity of major food crops in China showed a fluctuating upward trend. Compared with the US, except for wheat, the land productivity of rice, corn and soybean in China was lower than that in the US, and the average differences between China and the US during the study period were 16.60% (rice), 30.00% (corn) and 33.08% (soybean), respectively. At the same time, the gaps in corn and soybean present a widening trend. 2) The costs of corn and soybean production in China have always been higher than that in US. China's rice and wheat production costs surpassed the US in 2011. Since then, the cost of food crops production in China has comprehensively surpassed that of the US, and the gap between them has been widening. In 2016, the gap between China and US in grain production costs, from large to small, was soybean, corn, wheat, and rice. 3) The high cost of grain production in China is mainly due to labor costs and land rent, which account for more than half of the total cost, especially the labor cost (30%-40%), which is much higher than that in the US (less than 10%). Since the cost of grain production plays a critical role in price of grains in the market, the price of grains of China has fully surpassed that of the US. 4) In order to enhance the competitiveness of China's grain industry, it is necessary to further enhance the level of agricultural mechanization to reduce rising labor costs, improve the land transfer service system, reduce transfer transaction costs, and pay more attention to improving the level of grain yield per unit area, especially the low-yield crops such as soybeans.