improved plasmonic dichroic splitter based on three and four subwavelength metallic slits metal-insulator-metal (MIM) stuctures is proposed. Different visible lights passing through the multi-slits structure produce optical splitting effects by filling with different insulators and setting the slit width, thickness of the waveguide structure of multi-slits. The splitting effects are explained by using surface plasmon's principle and classical optics interference principle. Numerical simulation by the finite-difference time-domain (FDTD) method is conducted to verify the design. Compared to two subwavelength metallic slits structure, the higher splitting ratio can be achieved in multi-slits structures. Those MIM designs due to the advantage of simple structures can be obtained by using experimental equipment such as electron beam lithography. Therefore, it has good application in integrated optics and optical communication fields.