As trends of warming, elevated C0_2 concentration and excessive nitrogen deposition are expected to continue, it is necessary to know the consequences of environmental changes on terrestrial ecosystem process and services such as the orientation of community succession. Becasuse the deposition of phytoliths are controlled by physiological stages of plants,phytoliths are therefore allowing researchers to acquire more detailed information on botany. Moreover, as silica could perform functions of protecting plants from pests or diseases as well as reducing the toxicity of salt in crops, the content and size of phytoliths have important influences on plants. Thus, we set the study area at a grassland ecosystem experimental station (44°30′ ~ 44°45'N, 123°31′~123°56'E) of Northeast Normal University within the southwestern region of the Songnen Grassland ( Changling County, Jilin Province), selected two types of the dominant plants, Leymus chinensis ( C_3) and Phragmites communis (C_4),treated them by infrared radiator, OTC (an open-top chamber to elevate CO_2 concentration),and artificial nitrogen fertilization; and extracted their phytoliths to assess their responses to temperature and environmental changes. We extracted and then analyzed those phytoliths in leaves,paid greater attention to morphological and content variations of phytoliths within these two species when a certain environmental condition changes, trying to acquire the responses. The data show : warming and elevated C0_2 concentration had positive effects on phytoliths in L. chinensis, while the deposit of phytoliths in P. communis is restrained ; excessive nitrogen had negative effects on both L. chinensis and P. communis phytoliths, whereas warming could reduce the negative impact on excessive nitrogen in L. chinensis phytoliths. As the suppression of phytolith growth would reduce the mechanical strength and the insect-resistance capacity of plants,it is necessary to pay more attention to the physiological and biochemical changes in L. chinensis and P. communis. Elongate,blocky polyhedral,laminate,favose and rectangle were more sensitive to warming, elevated C0_2 concentration and excessive nitrogen, and could become some new indicators of environmental changes. In contract, phytolith oriented in short cells ( rondel and saddle) were more stable, and were not disappeared when environment was disadvantage. This result demonstrated the taxonomic significance of short-cell phytolith in the grass family.