Silicalite-1 samples were synthesized by two hydrothermal methods and modified with ammonia solution under different temperature and length of time respectively.The characterization researched by XRD,FTIR indicated that ammonia solution could change the crystal form and silanol type on Silicalite-1.The results of vapor Beckmann rearrangement of cyclohexanone oxime indicated that nest silanol were the main active sites,but the crystal form was not related to the silanol type and catalytic performance.Ammonia solution treatment could also eliminate the side reaction site of terminal silanol group of Silicalite-1 so as to improve the Beckmann rearrangement performance.