Abstract: The experiment was conducted with twenty-four grazing sheep divided into 3 experimental groups on the basis of body weights,i.e.control,optimal and non-optimal groups to study the effect of optimized supplementation on growth performance and rumen fermentation characteristics of grazing sheep in winter.The sheep in control were grazing only,whereas the grazing sheep in the optimal were supplemented with 250 g of an optimal forage mix and 404 g of concentrate1.The animals in non-optimal were supplemented with 465 g of concentrate 2.Weight gain rate in the optimal increased by 1.2% and 15.3 % as compared to that of the non-optimal and control group,respectively.Ruminal fermentation parameters were not significantly different between the optimal and non-optimal groups,however,they were significantly improved compared to the control.These results indicated that optimized supplementation strategies in winter were beneficial for markedly improving growth performance and rumen fermentation characteristics of grazing sheep.