The tilt of porous air bearing is caused by the nonuniformity of surface pores on the porous restrictor.In order to find a suitable method to evaluate the influence of permeability distribution on the tilt of porous bearings,the local fractal dimension of surface pores on the porous restrictor was obtained by the image acquisition,the distribution of local fractal dimension was employed to evaluate the nonuniformity of permeability,and the distribution vector was proposed to evaluate the tilt of porous bearing.The tilt angle and direction of porous bearing were measured in the working status.The experimental results indicate that the tilt of porous bearing can be forecasted by this nondestructive method,the more concentrated the distribution of local fractal dimension is,the more uniform the permeability is;the tilt angle can be estimated by the norm of distribution vector and the tilt direction is consistent with the direction of distribution vector.