Space trusses are three-dimensional structural systems which widely used in recent decades to cover large areas like halls, stadiums, and airports. The space trusses provided a lightweight and economical solution with fast construction. Traditional space trusses were made of hollow steel tube members that connected in joints of trusses. The paper presents a new composite technique to improve the behavior of space trusses.  The hollow steel members were replaced with concrete-filled tubular steel members (CFST). The paper presents an investigation of Space Trusses with CFST Members through finite element modeling. The space trusses had a real scale with square dimensions of 20000 mm x 20000 mm. The paper presented parameters like truss member length and CFST member's location. The investigation presented results like ultimate load and cross-ponding central deflection. The investigation reported the replacement of hollow steel members with CFST elements in space trusses, led to an improvement in the behavior of space steel trusses.