In order to clarify effect of steel ratio on the compressive behaviors of Concrete-Filled Steel Tube (CFST) and Reinforced Concrete-Filled Steel Tube (R-CFST) columns, investigations were performed based on the finite element (F.E.) method. Material models and analyses method which are applicable for R-CFST were proposed and the model was validated using known experimental results, and then 36 models of R-CFST and respective CFST with 6 different steel ratios were analyzed. Load-displacement response, load bearing capacity, contribution of steel to the strength on per unit area and ductility were studied. The results show that: the bearing capacity and ductility of CFST are higher than that of R-CFST with the same steel ratio when the concrete strength and steel ratio are lower, the bearing capacity and ductility of R-CFST tend to increase with the increase of concrete strength and steel ratio; strength contribution of longitudinal reinforcement of R-CFST on per unit area is higher than strength contribution of steel tube of CFST on per unit area, and R-CFST’s contribution is more significant as concrete strength increases ; when filled with high-strength concrete, R-CFSTs are more effective than CFSTs. In conclusion, configuring reinforcement in CFST is more effect than increase of the steel tube wall-thickness, especially when filled with high-strength concrete.