Abstract: In order to improve the accuracy of the breakthrough point in underground engineering, the indirect adjustment method with constraint conditions is adopted, that is, a constraint condition is added in the adjustment, so that the proportion of horizontal and vertical errors of ground control points to through points is equal.Under the principle of least squares, the ground control network is adjusted to obtain the coordinate values of the ground control points after adjustment.And this method was applied to a practice.The results show that the coordinates of the control points change after the additional constraint adjustment, and the penetration error of the control points to the breakthrough points is increased by 20% after the change, so as to ensure the quality and safety of the underground breakthrough project.