A superfocusing system is presented based on the theory of silver superlens and multi-phase binary optical elements. We get a single focal light spot with diameter of 0.36 λ and focal depth reached over 10 λ which calculated by finite-difference time-domain method (FDTD) and scalar diffraction theory. This feature makes it a promising to replace the probe of NSOM and to realize the super-resolution imaging and lithography and other applications.