High-yielding cultivation techniques such as plastic film mulching and high density planting are being used widely in northeast China in recent years, especially in those rain-fed agricultural regions. In this paper, the effect of plastic film mulching and planting density on corn yield and field soil moisture was studied in a rainfed agricultural region of Shenyang, Liaoning Province. The dynamic changes of soil moisture and corn yield were investigated in fields at three planting densities (60000, 67500, and 75000 plants·hm^-2) with/without film mulching. Consistent trends in soil moisture were observed for the different planting densities through the whole growth period, i.e., an increase in soil moisture with the rainfall and a decrease in the drought time, especially during jointing stage and filling stage of corn. The corn yield was greater in the film mulching fields than that in the unmulching fields at a same planting density, and the greatest increment of yield appeared at the density of 60000 plants·hm^-2 (by 14.3%). The influence of planting density on plant water use efficiency was more sensitive in the film mulching fields, compared to the un-mulching fields. Collectively, both increasing corn density and applying plastic film mulching can increase the corn yield, but lead to the decrease in soil water storage.