This paper explores a method to correct the image movement model of an off-axis Three-mirror Anastigmat(TMA) optical system to obtain higher mapping accuracy. Two kinds of line-array Off-axis TMA mapping cameras were modeled and the calculation formulas of image motion speeds and drift angles for the oblique-view camera and the nadir-view camera were deduced by considering earth curvature. By taking the off-axis TMA aerospace mapping camera with an intersection angle of 25° for an example, the influences of image motion speed matching remains and drift angle remains on the image quality of off-axis TMA aerospace mapping camera were analyzed at the oblique-view camera adjusted with the row transfer periods and their drift angles. Results indicate if more 5 TDI stages are used, the oblique-view camera and the nadir-view camera under a constraint of 5% MTF reduction should adjust their row transfer periods respectively; if drift angle of the oblique-view camera is adjusted according to the nadir-view camera, TDI stages should be no more than 71. However, If drift angles are adjusted by giving attention to the oblique-view camera and the nadir-view camera, the imaging quality for the both cameras has no essential influence at a TDI stage of 96.