Abstract: To evaluate the influence of different types of fine aggregate on the flexural behavior of concrete filled stainless steel tubes, a total of 24 concrete filled stainless steel tubular (CFSST) specimens were tested. The main test parameters include the types of fine aggregates, the cross-sectional shape and the shear span ratio. Based on test results, the failure modes of composite members infilled respectively with original sea sand, desalted sea sand and river sand were compared. The influences of the above factors on the load-deformation curve, the flexural strength and the flexural stiffness of the specimens were experimentally analyzed. The test results show that replacing river sand by original sea sand or desalted sea sand has minor influence on the flexural strength and the flexural stiffness of CFSST specimens. A finite element (FE) model was then established to simulate the behavior of CFSST members under pure bending, with further parametric studies performed. Finally, simplified models for calculating the bending capacity of the circular and square CFSST beam were proposed to provide reference for practical applications.