Abstract: The strength analysis of control network has long been limited to the description of the precision of the elements of the network.Recently,the reliablity analysis was developed.We now propose that "deformation strength analysis" must be included in the strength analysis of control network.It is considered that the quality of networks can be judged from the point of view of the deformation of networks which is represented by the principal displacements of the netpoints due to the errors of observations.In this paper,the methods of "deformation strength analysis" is presented,and their characteristics are demonstrated by some practical examples.In addition,some extension of the traditional methods of the precision analysis is made.