This paper derives a simulation model that examines the food security of the grain producing households in China in an open border model regime. We define a food inadequacy index (F.I.) to measure the change of the food security status under alternative scenarios of border liberalization for the households. We conclude that if opening the border of grain market is followed by a more variable grain price distribution, the food security status will deteriorate for the low-income households on average. However, if border liberalization is followed by a decrease in mean of the price distribution, even with a more variable distribution, the food security status improves.