Abstract: In order to develop the resource of plant ice structure proteins(ISPs),alfalfa ice structural proteins(AISPs)were extracted from alfalfa hay by ammonium sulfate precipitation method in this study. The thermal hysteresis activity(THA)was measured and the changes of ice crystals were observed. Then AISPs was added to frozen dough,and the texture properties tensile properties and micro-structure of frozen dough after several periods of freeze-thaw cycles were measured. The results showed that the THA of AISPs was 0.61 ℃. When AISPs were compared with NaCl and sucrose solution,it had more ice crystals and smaller volume after four times of freeze-thaw cycles. It identified that AISPs had antifreeze activity in a certain extent. With the increasing of freeze-thaw cycles,when AISPs were added from 2.0% to 2.5%,many performance of frozen dough were increased observably,such as elasticity,cohesiveness,adhesion,extension area and ductility(p<0.05). The hardness of frozen dough was reduced. The tarch granules were destroyed less and the gluten networks were became clearly. AISPs displayed good protection effect on frozen dough to improve the quality of frozen dough,and the frozen storage stability was improved obviously.