In this paper,we propose a locally linear estimation of a regression discontinuity model.The proposed estimator is applicable to evaluation of the effectiveness of the program treatment,and it improves upon the existing literature by providing not just the treatment effect at discontinuity but also insight of the treatment effect on those near discontinuity.Under some familiar conditions,we establish the consistency and asymptotic normality of the proposed estimator.We also provide an easy to compute consistent covariance matrix.