In order to make clear mechanism of photosynthesis of spring maize in northeast of China cultivated with different row spacing, two varieties, Xianyu 335 and Jundan 8 were used as material in the field experiment.Randomized block design was adopted and four row spacing set, i.e., 70 cm, 65 cm, 60 cm and 50 cm. It focused on the effect of community with different row spacing, mainly on concentration of carbon dioxide, light intensity and the rate of net photosynthetic for functional leaves at different levels of canopy, i.e., field upper layer（2.15 m above theground）, middle（1.2 m above the ground） and lower（0.25 m above the ground）. The results showed that average con-centration of carbon dioxide in 70 cm row spacing treatment was 403 mg/L, which was significantly higher than that of 65 cm, 60 cm and 50 cm row spacing（348 mg/L, 329 mg/L and 341 mg/L, respectively）.This indicated that plant-ing model with wide row spacing and narrow in-row spacing was favor of ventilation. Average light intensity in 50 cm row spacing was 16 092 lx, which was significantly higher than that in 60 cm, 65 cm and 70 cm row spacing（14981 lx, 10 893 lx and 10 095 lx, respectively）. This indicated that planting model with wide in-row spacing and nar-row row spacing was beneficial light transmitting. The average net photosynthetic rate of two species at the stage ofwax stage was 8.40 μmol CO₂·m^-2·s^-1and 8.76 μmol CO₂·m^-2·s^-1in 60 cm and 65 cm row spacing, 10.57 μmol CO₂·m^-2·s^-1and 11.14 μmol CO₂·m^-2·s^-1in 50 cm and 70 cm row spacing. This indicated that affected by air and lightconditions, the net photosynthetic rate of spring maize maintained a higher level in 70 cm and 50 cm row spacing in late growth stage.