Songyu419 was used as materials and planted at five density, 50, 60, 70, 80 and 90 thousand plants perhectare. A field experiment was carried out to study effects of plant density on grain yield and yield components ofspring maize with mechanized sowing. The results proved that with the increasing of planting density, grain yield in-creased firstly and then reduced, however there was no significant difference between the treatments. It suggestedthat the best planting density in Jilin area was 67 762 plants/ha（65-70 thousand plants/ha） for Songyu419, with abig ear and medium resistance to compact planting. We proposed that the key cultivation measures with higher yieldwere to reduce the percent of empty stalk and the length of bald tip.