The control parameters for a synthetic jet acting on a separated flow over hump are optimized using multi-objective optimization and effects of separation control are discussed. The following three parameters are used for operation of a synthetic jet: a synthetic jet position, a maximum velocity of jet and a synthetic jet frequency. A direct numerical simulation is performed by solving compressible, unsteady, laminar flows over a half cylindrical hump in two dimensions, and effectiveness of each operation of a synthetic jet is investigated. The optimization results show that periodic actuation improves aerodynamic coefficients. In particular, the performance of the synthetic jet placed around the top of the hump is better than other positions. It is found that the lift coefficient is maximized when a synthetic jet act at a low frequency in forward. Also it is found that the drag coefficient is minimized when a synthetic jet act at a high frequency in backward.