Abstract: On the basis of gravity field model(EIGEN_CG01C),together with multi-altimeter data,the improved deflection of the vertical gridded in 2′×2′ in China marginal sea and gridded in 5′×5′ in the global sea are determined using the weighted method of along-track least squares,and the accuracy is better than 1.2″ in China marginal sea.As for the quality of the deflection of the vertical,it meets the challenge for the gravity field of high resolution and accuracy.It shows that,compared with the shipboard gravimetry in the sea,the accuracy of the gravity anomalies computed with the marine deflection of the vertical by inverse Vening-Meinesz formula is 7.75 mGal.