Abstarct: The weeds are a major constraint limiting crop yield in agricultural and in organic systems in particular. Improving the rate of germination and crop growth in early season via increasing crop competitiveness can increase the competitive ability of crops with weeds and reduce weed damage. In this regard, in order to investigate the effect of seed pre-treatment with cold plasma on the growth and yield of cowpea (Vigna sinensis L.) and weed control, a factorial experiment was conducted as randomized complete block design with three replications at the Research field of Faculty of Agriculture, Shahrood University of Technology, in 2016. Experimental factors were including cold plasma at six levels: control (no treatment), hydro-priming of seeds with distilled water for 10 hours, pretreatment of seeds with plasma radiation for 15 seconds, hydro-priming of seeds for 10 hours + plasma radiation for 15 seconds and weed control at three levels: control (no weeding), weeding all season and application of trifluralin (1200 g ai/ha). Results showed that, pre-treatment of seeds by cold plasma and hydro-priming increased significantly the most studied traite in weedy condition than control. Also, pre-treatment of seeds by cold plasma increased distance of first pod from the soil surface, leaf and stem dry weight, pod length, 100-seed weight, seed and biological yield and protein percentage in the presence of weeds than control (no pre-treated seeds) significantly. In weed inferst condition, plant height, leaf area index, 100-seed weight, leaf water content, stem weigth, the number of branche, seed and biological yield and protein percentage of cowpea increased by hydropriming of seeds than control (no pre-treated seeds) significantly. Weed density and biomass decreased by 68 and 57% in cold plasma treatment compared to control (no pre-treated seeds) respectively. Also, cold plasma treatment increased cowpea yield 36.9 and 43.5% respectively in weedfree and weedinfest conditions than control. baxsed on the results of this experiment, the use of seed pretreatment methods such as hydroperiming and cold plasma could significantly increase the growth characteristics and yield of cowpea through increasing of the crop competitive ability.