Depending on in which season or in which section of rangeland livestock grazes, it shows certain behavior. Present study is therefore aimed at exploring preference value of species in Saleh Abad rangelands of Ilamprovince from 2007 to 2010. In this study, the preference value of 17 species and annual plants was investigated through the method of percent of consumption. The results showed that the effect of year, month and plant species on preference value is significant. Due to drought, average preference value in 2008 was more than that in 2007, 2009 and 2010, respectively. Preference value of rangeland species was higher in April than in March and statistically the difference was significant. Results showed that the species Ankyropetalugypsophiloides, Annual grass & forbs, Salvia compressa, and Sanguiosorba belong to Class III and of moderate palatability. Other non-palatable species were categorized in class IV and V. In study area, the last two months of grazing season (March and April) matched the first two months of plant growth. Annual grasses and forbs species and Sanguiosorba minor were equally consumed by animals in both March and April.Toward the end of the grazing season (end of April) perennial species are consumed. For example, relative consumption of Salvia compressa and Ankyropetalum gypsophiloides was and 92 percent, respectively. In April, an increase in consumption trend of other perennials was witnessed. Therefore, with presence of livestock in from April to June, fresh forage of perennial herbs is grazed by livestock but farmer s believe that the amount of forage production of perennial herbs is not enough that forces the livestock out of rangeland.