Abstract: To solve the problem of the lack of effective all-composite truss torsional stiffness characterization method except for experiment, based on the homogenization concept and according to the principle of equal single cell shear stiffness, the all-composite truss was equivalent to closed thin-walled beam to deduce their equivalent torsional stiffness firstly. Then the displacement conversion method was proposed and the torsional angles of truss were measured, and an experimental investigation on all-composite truss torsional stiffness was conducted. The fine joint models were embedded into truss model of beam elements to simulate and analyze the all-composite truss torsional stiffness finally. The results show that equivalent and simulative results agree with experimental values basically, which indicates that the equivalent analysis method can predict all-composite truss torsional stiffness effectively, and the truss simulation model has certain engineering practicability. Moreover, the experimental scheme is reliable, and the proposed displacement conversion method can solve the problem of larger relative errors of small angle measurement.