FRP-confined concrete-encased cross-shaped steel column (FCCSC) consisting of outer square glass-fiber-reinforced plastic (GFRP) tube, internal cross-shaped steel and the filled concrete is a novel type of composite column. In this study, the eccentric compression behaviour of FCCSC specimens was investigated based on OpenSees software to further complement the experimental deficiencies. The applicability of the numerical method was verified by comparing with the experimental results. In addition, the effects of load eccentricity and slenderness ratio on the eccentric compression performance of FCCSC components were fully explored through parameter analysis. The analysis results indicate that an increase in load eccentricity and slenderness ratio leads to greater lateral deflection in FCCSC eccentric compression components, along with a reduction in ultimate axial force and initial stiffness. Furthermore, the slenderness ratio has a significantly greater impact on lateral deflection compared to load eccentricity.