Abstract This paper presents an investigation of a new type of seawater sea-sand concrete (SWSSC) beam which consists of BFRP bars/grids and BFRP-wrapped steel tubes (BWST). The transversally placed basalt fiber-reinforced polymer (BFRP) grid units act as shear stirrups, while the longitudinal BWST near the bottom area is used to improve the tension resistance. The flexural behavior of the hybrid SWSSC beams under different BFRP reinforcement ratios with or without the BWST were experimentally tested and compared. In addition, a finite element model (FEM) was established and a parametric study was conducted to show the influence of key parameters. The results showed that the placement of the BWST could significantly improve the mechanical properties of the hybrid beams, especially in terms of improving the flexural stiffness and reducing crack width. In addition, the full-length embedded BWST could shorten the height of the vertical cracks developed along the FRP grids, and denser diagonal cracks developed in the shear span.