Rapid Prototyping (RP) technique was used to prepare porous Ti6Al4V with designed structures. Firstly, a 3-D interconnected porous wax mold with uniform pore size and porosity was designed by computer aided design (CAD), and fabricated by 3-D printing machine, then an aqueous Ti6Al4V slurry prepared from Ti6Al4V powder and binders was cast in these molds. The green bodies were subjected to drying, debinding and finally sintering at a high temperature and a high vacuum to obtain porous Ti6Al4V. Optical microscopical observation, scanning electronic microscopical observation, mechanical test were performed on the obtained porous Ti6Al4V with regard to the porous structures and mechanical properties. The porous Ti6Al4V made by RP technique posses designed structure with uniform pore size, porosity and interconnection. With the computer aided design, it is easy to improve the mold structure with predicted or controlled macrostructure and microstructure according to the custom requirement.