The invention discloses raw materials of a lithium ion battery separator with smoothness, and the lithium ion battery separator with the smoothness is made of polyolefin resin and smooth agents. The invention further discloses a method for processing the lithium ion battery separator with the smoothness by means of the raw materials. The method comprises the following steps that 1, the polyolefin resin, the smooth agents and other additives are stirred evenly through a stirring mixer to obtain a first mixture; 2, the first mixture is added into an extrusion tape casting system, and then sheet casting is performed to prepare precursor films; 3, the obtained precursor films are placed in a constant temperature oven, and then annealing treatment is performed; 4, the annealed precursor films are compounded into multiple layers, then longitudinal stretching is performed, and the separator with cellular structures is prepared. According to the lithium ion battery separator with the smoothness and the separator processing method, the prepared separator is good in smoothness, low in cost and simple in processing procedure.