In the engineering survey of Yangtze River waterway,the correction of length deformation in Gauss projection is especially important. The rapid static positioning can quickly acquire the accurate coordinate and baseline information. In case that the influence of the earth curvature on horizontal distance can be ignored,this paper illuminates an original method which employs the exact baseline information acquired by rapid static positioning to calculate the real distance using the baseline horizontal projection on ellipsoid tangent plane,and finally corrects the length deformation. The results indicate that,the deviations between corrected distance and the corresponding distance measured by the total stations are all at cm level,and the maximum deviation is 1.4 cm,which satisfies the requirement of the engineering survey of the Yangtze River waterway.