In order to study the mechanical performance of the connection nodes of double web I-beam GFRP waist beam in deep foundation support, two sleeve type connection methods of GFRP waist beams were tested with two points of symmetric loading footage, and the three-dimensional numerical models of the two connection methods were established with the help of ABAQUS finite element simulation software to analyze the force performance of GFRP waist beams with different connection methods, and the span section of waist beam was taken as the object of study to reveal the transverse deformation law of the connection. The transverse deformation law between the sleeve and the GFRP waist beam is studied, and the limit states and damage forms of the GFRP waist beam members with different connection methods are mastered. The results show that the double web I-beam GFRP waist beams have high bearing capacity and good stability of the members; the use of built-in steel sleeves to connect the members has less deformation, higher node bearing capacity, easy installation on site, and can realize the recycling of waist beam members in foundation pit support, which is a reasonable connection method for GFRP waist beam construction on site.