Knowing weed species and dominant population situation in the corn field under different ecological environment condition has important significance to draw up a comprehensive treatment scheme to control weed by using herbicides and other supporting measures.An investigation of weed species and their population in corn field of Jilin Province was carried out.The results indicated that there were 39 species of weeds,which belonging to 16 families.Main weeds population in different ecological zones of Jilin Province was gained according to the damage level and situation of dominant population.