The Concrete-filled Steel tube columns known as CFT are also called composite columns. These columns consist of steel tube which is filled with concert. Their advantages in comparison with reinforced concrete and steel columns have made their usage more prevalent in high rise buildings. In order to analyze the statistic behavior of concrete-filled Steel tube columns, the ABAQUS was used. For studying the stiffener effect, reinforced and non-reinforced concrete usage, and cohesion ratio between steel and concrete, 16 columns were modeled. They were three meters in length with a pinned support at each extreme end. The results indicated that using stiffener increases the load-bearing capacity of the filled columns to about 8 to 10 percent more than the hollow ones. Comparing the eight other models, the columns using reinforced concrete have a 10 to 28 percent load-bearing capacity more than columns filled with non-reinforced concrete. Furthermore, the columns with 100 percent cohesion ratio had an 8 to 16 percent load-bearing capacity more than the columns with 20 percent cohesion ratio