Geodetic control networks have been used for more than 200 years by peculiar national system, both to establish the size and shape of the earth, and to determine the positions of points on its surface. Junction schemes for the densified geodetic network are proposed to the case whether the accuracy of existing network is known or unknown, in this paper. The concepts of adjustment, under the condition of partial $X^TX$＝min., is applied to densification system. Moreover, the technique of epoch analysis, which is often used in small deformation survey net, is introduced to the national control network for unstable point detection.