To determine the effect of intercropping on the growth and development of weeds, the experiment in the Agricultural Research Station of Lorestan University 2014-15 and 2015-16 as rain fed was conducted in factorial randomized complete block design (RCBD) with three replications, in one place with weeds factor in 4 levels (full weeding, one-time weeding, two-time weeding and non-weeding or control) and additive series intercropping factor in 5 levels, 0: 100 (sole cropping of barley), 40: 100 (broad leaf vetch: barley), 70: 100, 100: 100 and 100: 0 (sole cropping of vetch). Intercropping of vetch: barley in comparison with sole cropping treatments, by increasing weed control efficiency (WCE) was represent reducing of the species number, its growth and development, On the other hand the year factor, on the role of the intercropping system and completing the effect of this method was effective on growth and development of weeds, So in the first and second years, ratios of 100: 100 and 70: 100 (vetch: barley) in preventing the development of natural flora, were known to the right combination.