Herbivore foraging is often influenced by plant community composition which determines both diet selection and nutrients intake of animals that impact on the vegetation. This has been affected by plants characteristics like physical traits, in which plants reduce animals’ consumption through features such as spines, thorns, irritant chemicals, dense growth, or behavioral factors, which make herbivores give up feeding even if they have access to target plants. However, there is also an increasing amount of literature which indicates that defense traits of the neighboring plants can influence the degree of herbivore foraging selectivity. Many previous studies use manipulated experiments to test herbivore foraging response to plant associational defense. But our studies provide such a test in artificial grassland which is more applicable to a natural grassland ecosystem.We examined the effects of plant neighboring relationship on large herbivore foraging in order to identify the foraging mechanism of large herbivore which resulted from different plant associational defenses. This study was conducted at the Grassland Ecological Research Station of Northeast Normal University, Jilin Province; P. R. China. Two plant spatial relationship treatments of30m X30m were established with four replications. For each plot three patches were created using combination distribution pattern of three plant species with different spatial neighboring relationship. The first plot consisted of the focal plant Kalimeris integrifolia with a preferred plant, Lathyrus quinquenervius as a neighbor plant. Second plot consisted of the focal plant the Kalimeris integrifolia with Leymus chinensis, a less preferred plant as a neighbor plant. And then a total of15two-year-old female body weight （body weight34.2±0.81kg） Northeast fine-wool sheep breed in northeast China were used at this experiment.The results showed that sheep selectivity of Kalimeris integrifolia in good neighbor treatment was lower than that of the bad neighbor treatment. For that case good neighbor treatment provides good protection for the focal plant. And also, sheep foraging selectivity within-patch was stronger than between-patch scales which result in neighbor contrast and susceptibility outcomes. At the good neighboring treatment focal plant gain protection from its palatable neighbor, but on bad neighbor treatment the focal plant was susceptible to be attacked by herbivores through contrasting itself with less preferred neighbor. On the other hand, the results indicate that it is not a single factor which leads to consumption of the plants. For instance, palatability of the plant, quality and abundance of the neighboring plants, characteristics of the neighboring vegetations, grazing intensity and heterogeneity of the available vegetation.However, the foraging mechanisms revealed the cognitive mechanisms which involved in learning and memory, and played a great role in foraging of animals. Sheep seemed to have great spatial memory, so whenever foraging intensity was changed; the sheep could find the places having palatable plant species. This was revealed by the number of bites and food intake for each plant species at each treatment.In conclusion, we found that sheep were more selective on within-patch than between-patch scales; and hence plants with good neighbor relationship would get protection from sheep grazing. All these findings can help us to understand grassland managements and biodiversity conservation better.