Because of the poor observability of Inertial Navigation System on stationary base, the estimation error of the azimuth will converge very slowly in initial alignment by means of Kalmari filtering, and making the time initial alignment is longer. In this paper, a fast estimation method of the azimuth error is creatively proposed for the initial alignment of INS on stationary base. On the basis of the the fast convergence of the leveling error, the azimuth error can be directly calculated. By means of this fast initial alignment method, the time of initial alignment is reduced greatly. The computer simulation results illustrate the efficiency of the method.