A field experiment was carried out for two years to investigate the increase of dent corn yields when intercropped with 3 different planting densities of soybean. Dent corns planted at a spacing of 80 cm × 40 cm, intercropped with soybean planted at the densities of 6, 25 and 38 plants/m2, were observed in a completely randomized block design. The results were as follows. The Crop Growth Rate (CGR) and Net Assimilation Rate (NAR) of dent corn at 8 to 9 weeks after planting were the highest at the soybean density of 25 plants/m2. The Specific Leaf Area (SLA) significantly increased at 38 plants/m2, and the NAR decreased at the same density. The corn grain yields, harvest index of dent corn and percentage of nitrogen contents of corn grain, increased at the densities of 6 and 25 plants/m2. The highest grain yield and harvest index were obtained at 6 plants/m2, but the highest value of the Land Equivalent Ratio (LER) was obtained at 25 plants/m2. The result of this experiment indicated an enhancement of growth and yields of dent corn intercropped with soybean. This was done by the balance between the relative advantage and the relative disadvantage caused by the intercropping.