Extruded products with precision shape have been used widely to 3C products, electronic equipment, communicatory installation, precision instrument, automobile industry. The tolerance for this kind of asymmetric products with small size is strictly required. During extrusion, the plastic flow of the billet inside the die cavity is complicated. The temperature distribution of the billet, the elastic deformation of the die, and the design of the flow guide affect the final dimension of the product. This paper uses the finite element code ¡§DEFORM 3D¡¨ to simulate the plastic flow of the billet inside the die cavity and the stress, strain, temperature distributions of the die during extrusion of a 3C product, Clip and Housing. From the simulation results, a die design guideline is proposed and the temperature, stress, strain distributions are discussed systematically. Furthermore, extrusion experiments are conducted. From the comparisons of the temperature at the die exit, the product sizes and the extrusion force, the validity of the die design rule is verified.