The invention relates to the technical field of molecular distillation, in particular to a membrane scraping device of a molecular distiller. The membrane scraping device comprises a driving shaft, aconnecting rod and a membrane scraping mechanism, the membrane scraping device is arranged in a distillation cylinder, and the membrane scraping mechanism comprises a flow equalizing plate, an air bagstrip, a positioning plate, a rotating shaft and a bottom plate. One end of the flow equalizing plate is vertically and fixedly connected with one end, close to the inner wall of the distillation cylinder, of the connecting rod, the other end of the flow equalizing plate is vertically downward, and the flow equalizing plate is not in contact with the inner wall of the distillation cylinder, so that mechanical friction between the flow equalizing plate and the inner wall of the distillation cylinder is avoided; a liquid guide groove is formed in the surface, facing the inner wall of the distillation cylinder, of the flow equalizing plate, a certain inclination angle is formed between the liquid guide groove and the movement direction of the flow equalizing plate, and the liquid guide groove can enable a liquid material to forcibly move downwards along the track of the liquid guide groove. Therefore, mechanical friction between the flow equalizing plate and the inner wall of the distillation cylinder is avoided, certain abrasion is reduced, and the service life is prolonged.