A reflecting ring focusing system for laser propulsion has been designed. A paraboloidal reflector of higher order is constructed to focus the laser energy on a ring which can produce a tire liked ignition region in the thruster. Considering the angle of laser incidence and reflector's coarseness, mathematic models of the focusing performance have been set up through ray tracking method. Moreover, numerical simulations of the shape, size, energy density and spatial characteristics of ignition wire are carried out in order to know the ring focusing system's superiority. The results show that the ring ignition region with a radius of 49 mm produced by a ring focusing system is about one order of magnitude larger than that produced by single point focusing system, which makes the heating of the work substance much more uniformly. Also, the ring focusing system has a better coarseness endurance.