Ultrasonic longitudinal vibration assisted helical milling (ULVAHM) can significantly improve the machining quality. However, the complex kinematics can result in a more complex morphology of the surface machined by ULVAHM than that by a conventional helical milling. To predict the morphology and summarize the rules of the machined surface generated by ULVAHM, a morphology prediction model and its visualization method were proposed in this study, and a verification experiment was conducted to compare the three typical microscopic characteristics, namely, wave texture, sharp-like peak and segmented layer. A favorable agreement between experimental and simulation results was demonstrated. Afterwards, the effects of amplitude, rotational speed, revolution feed and tangential feed on the surface morphology were evaluated by using the model. The investigation results show that the amplitude in ultrasonic vibration leads to the formation of wavy patterns on sidewalls. As the spindle speed increases, the wavy pattern weave becomes sparser. Meanwhile, the height of oblique crest band, the spacing of split layers, and the height of shaped projection are determined by the circumferential feed per tooth, axial feed per tooth, and feed speed, respectively.