Abstract: Beam deflection of a monospeckle laser beam propagating in a plasma with parameters relevant to Inertial Confinement Fusion is investigated using three dimensional Euler laser plasma interaction code LAP3D. Effects of the beam intensity and the speed of the transverse flow on the beam deflection are analyzed. Simulation results suggest that the beam deflection is caused by laser self-focusing and plasma transverse flow. It is found that the beam deflection is evident only when the speed of plasma transverse flow is closer to that of ion acoustic wave and the angle of the beam deflection is in proportion to the laser intensity. When the speed of plasma transverse flow becomes lower than that of ion acoustic wave, the beam deflection is suppressed. When the speed of plasma transverse flow becomes larger than that of ion acoustic wave, refraction effect becomes dominant.