The study was conducted in order to identify the weed species in onion fields in Chhattisgarh plain . An experiment was conducted during rabi season (October-March) of 2008-2009 to find out the effect of weed management practices on growth and yield of onion, weed dynamics and economics. Onion variety “Nasik Red” was grown as a test crop and transplanted on 20th November 2008 with spacing 15x10 cm. A total of seven weed species belonging to seven family were identified in onion field that were surveyed. The maximum weed density (20.62%) was recorded with Parthenium hysterophorus followed by Cyperus rotundus(19.35%) and Cynodon dactylon (19.00%). The result obtained amoung ten treatments revealed that higher numbers of leaves per plant noted in hand weeding twice at 20 &40 DAT similarly maximum bulb girth(4.81 cm) and bulb weight(93.00g) was recorded under hand weeding twice at 20 &40 DAT. The treatment oxyflourfen @ 0.20 kg ha-1 pre-transplanting + hand weeding at 20 DAT resulted in greater plant height, weed control and yield under Chhattisgarh plains situation