Abstract: This aeronautical structural analysis system for static analysis（H AJIF-I） is the first large software system developed by the Chinese Aeronautical Establishment（CAE）. By using multilevel substructure analysis and finite element displacement method, this system is suitable for various linear static analysis of aeronautical structures. The maximum capacity of the system is as follows: 3000 nodal DOF of each substructure, 99 substructures. 10 levels of substructures. The system provides some statements for automatic data generation, so the initial data necessary for computation can be generated automatically. There are also several special statements for structural analysis, thus enabling user to organize his own computation flow, The system offers two solvers for high order sparse matrix, i.e. a modified variable bandwidth method and a hyper-matrix method. One of these methods will be chosen by users according to computer capacity and structural characteristics.The system consists of a sequence of functional modules which are independent of each other, so it can be modified and extended easily.There are approximately 30,000 source statements in the system and most of them were written in FORTRAN IV. At the end of this paper, a user's specification for stress analysis of an aircraft is presented as an example to demonstrate that the system is easy to handle.