A two-grid technique for solving the steady incompressible Navier-Stokes equations in a penalty method was presented and the convergence of numerical solutions was analyzed. If a coarse size H and a fine size h satisfy H=O(h1/3-x)(s=0(n= 2);s=1/2(n = 3),where n is a space dimension), this method has the same convergence accuracy as the usual finite element method. But thetwo-grid method can save a lot of computation time for its brief calculation. Moreover, a numerical test was couducted in order to ver-ify the correctness of above theoretical analysis.