Abstract: The data processing method for tunnel control network of accelerator has some shortcomings, such as the lackness of theoretical basis for determining deformation points, the risk of discarding stable points or including deformed points and the difficulty in judging the overall deformation of the control network. In order to make up for these deficits, according to the theory of 3-D control network deformation detectability, the expression of sensitivity ellipsoid was derived, and the deformation detectability property and the distribution of sensitivity ellipsoids for two typical accelerator tunnel control networks, linear and ring type, were analyzed as typical examples. The results show that the vertical sensitivity is lower than horizontal sensitivity in the two control networks, the sensitivity of control points on both ends in linear type control network is lower than that of the middle control points, and the sensitivity of control points in ring type control network is basically identical. On the basis of stability analysis theory of 3-D control network, by utilizing the integer stability test and mean gap method, the measured data of Shanghai Synchrotron Radiation Facility in 2016 and 2017 were taken as example to analyze its stability. The results show that the order of stability from strong to weak is ground points, external wall points, serrated wall points and pillar points, which is helpful to accurately analyze the deformation rule of control network and guide the adjustment of components.