Abstract: Based on the updated total Lagrangian formulation an incremental finite element theory for elastic large deflection of space trusses is derived in this paper. The stiffness matrix obtained in this paper has a symmetric and concise form in which the large deftection effects on structures can be included accu rately. Numerical examples show that the incremental finite element method presented in this paper can analyse the geometrically nonlinear problems of space trusses satisfactorily and effectively.