In this study, a total of 720 rainbow trout (Oncorhyncus mykiss) having 50.08±0.19 g of average initial weight were used to compare of usage of the soybean meal, sunflower meal, canola meal and cottonseed meal as the best plant protein source. Four different feeds which contain soybean meal (SBM), canola meal (CM), sunflower meal (SFM) and cotton seed meal were used, respectively. Four trial groups were tested in triplicate during 12 weeks. Experimental diets were prepared as isonitrogenous significantly difference among the groups for average feed consumption, condition factor and survival rate, however, average (42% CP) and isocaloric (13.9 MJ DE/kg feed). At the end of the study, it was observed that there was no live weight, live weight gain, feed conversion ratio (FCR), protein efficiency ratio (PER) and specific growth rate (SGR) were found statistically significant (P<0.05). Moreover, the difference in the composition of carcass and total body between the groups were found statistically significant (P<0.05). Consequently, it is concluded that soybean meal, canola meal and sunflower meal can be used as a part of fish meal, however cottonseed meal can be used as only smolt or older trout feeds if it is cheap and has good quality.