To study the mechanical behavior of Cold-formed Thin-walled Steel （CFS） C-shaped compression members strengthened by batten plates， the nonlinear finite element model of C-shaped steel was established by using ANSYS software. The correctness of the modeling method was verified by comparing the test failure characteristics and ultimate bearing capacities. The effects of batten spacing and eccentricity on the ultimate bearing capacity and buckling mode of batten-strengthened CFS C-section members under axial and one-directional eccentric compression were studied. The results showed that， with the decrease of batten plate spacing， the buckling deformation of C-shaped members changed gradually from distortion buckling to local buckling， and the ultimate bearing capacity of axial compression and eccentric compression members increased gradually. With the increase of eccentricity， the ultimate bearing capacity of eccentric compression members decreased gradually. It is suggested that the batten spacing of CFS C-shaped steel axial compression and eccentric compression members strengthened by batten plates should be taken as λ/3 and λ/4， respectively. Based on the mechanical characteristics and direct strength method of CFS C-shaped steel members strengthened by batten plates， a modified formula for the ultimate compressive capacity of CFS C-shaped members strengthened by batten plates was proposed， and the accuracy of the formula was verified.