In this study, the effects of sharp-crested sill on the characteristics of hydraulic jump formed in a gradually expanding stilling basin of rectangular cross section was investigated. The expansion of the basin is accomplished by increasing the bed width in the stream-wise direction. A total number of 228 tests were carried out for the range of initial Froude number from 3.1 to 10.3. Sills with various heights and different locations, relative to the jump toe, were installed in the basins with the diverging angles of 3, 5, and 9 degree. In all tests, the main characteristics of hydraulic jump including sequent depth ratio, relative length of jump and the relative energy loss were measured. The results indicate that installing sharp-crested sills have insignificant effect on the sequent depth ratio but may considerably decrease the length of jump. In addition, observations indicate that sills may improve general conditions and features of gradually expanding hydraulic jump in a rectangular channel