Abstract: It is already confirmed that the riblets on the shark skin have the function of drag reduction, however, it is very difficult to achieve on surfaces of complex casting parts for such bionic non-smooth surface, which seriously restricted its engineering applications. This paper took non-smooth structure of triangle section as a example, and took the centrifugal pump impeller surface of rib-like on the type of 200QJ50-26 as a carrier and discussed a casting forming principle and process of bionic non-smooth surface. First, according to designing request, rib-like non-smooth structures were sculptured using knife and ruler on the hard rubber pad. Second, heat-resisting lacquer was spread evenly on the two side of the riblet and made them natural drying. Third, utilizing the characteristic of rubber, the rib-shape rubber was adhered to the sand moulding surface of impeller according to the shape of it. Finally, cast molding. Selecting heating-resisting lacquer and painting it play a vital role in casting process .The sharp edges of the triangle groove that meet the design requirements can be formed by using a casting shaping method of bionic non-smooth surface, and non-smooth surface can be formed in the full port of impeller internal, and this method adapts to the processing of the non-smooth surface of complex parts.