Abstract: To study the suitable plant density of summer maize and keep high yield of summer maize in the North China plain. Field experiment was conducted to study the effects of different row spacing, planting distance and their interactive effects on the yield and yield components of summer maize. Split plot design was used with row spacing of 60 cm and 50 cm in the main plots and plant distance of 22 cm, 25 cm, 28 cm and 33 cm treatments in the sub-plots. The results showed that, the yield of 60 cm row spacing treatment was lower than that of 50 cm row spacing treatment. With 50 cm row spacing, the yield with 25 cm and 28 cm plant distance treatments were much higher. There was no significant difference between the two treatments. 22 cm plant distance treatments produced the lowest yield, and the yield of 33 cm treatment was in middle. With 60 cm row spacing, the yield with 22 cm and 25 cm plant distance treatments were much higher. There was no significant difference between the two treatments. 33 cm plant distance treatments produced the lowest yield, and the yield of 28 cm treatment was in middle. Row spacing and planting distance significantly affected the kernels per spike. Wide row spacing and wide plant distance increased the kernels per spike. Seed weight was less affected by row spacing. There was no significant difference between 60 cm and 50 cm row spacing in seed weight. The highest seed weight was achieved with the treatments of 28 cm and 25 cm plant distant. There was significant difference among the treatments. The results showed that the combination of 50 cm row spacing and 28 cm plant distant was beneficial to high yielding of summer maize in the North China Plain.