Abstract: Factors (topograph structure, basic flow) affecting ray characters of two dimensional Rossby wave are examined in this paper by numerical experiments. The numerical expriment results show that: (1) under conditions of west basic flows and ideal topography of half ellipsoid,there is a wavetrain with a parabolic route in the east of the topography; (2) wavetrains of vertical motion disturbance may propagate southward; (3) under conditions of the r=al topography and westerlies,the wavetrain path shows a sine wave,and vorticity deviations forced by zonal sea-land thermal differences also show a sine wave pattern.