Abstract: To reshape the beam of paraboloidal reflectarray antenna on satellite, random round method is used to optimize the phase. Firstly, the optimization of discrete phase is transformed into continuous problem, and then the Minimax method is adopted to search the optimization result, finally this result is rounded to get the array phase. To illustrate the validity of this method, the numerical simulation results of a paraboloid reflectarray antenna at Ku-band is presented. The results show that the method can realize the control ability of the beam shape, improving the flexibility of the antenna on orbit greatly.