Abstract: Image noise and outlier always exist in the estimation of fundamental matrix.As a result,a new method is proposed based on projective space.First,a special fundamental matrix is defined including only 5 parameters according to the projective standard basis of three-view geometry.The method can cope with mismatch and search for the best 7 correspondence points to estimate epipolar geometry based on RANSAC(random sampling consensus)technique according to the principle of the minimal re-projection error.Many experiments with both synthetic and real images show that our method can obtain fundamental matrix with high accuracy.