The application of aluminium alloy space structures is increasingly widespread. There is a new single-layer aluminium alloy spatial grid structure with H-shaped members web openings nowadays. In this paper, the flexural performance of H-shaped aluminium alloy members with web openings in this structure is studied through experiments, finite element analysis and theory. Parametric analysis is carried out to study the influence of initial imperfections, opening parameters and section properties on the flexural performance of the members. The conclusions are as follows: (1) The presence of initial imperfections can significantly reduce the ultimate load-carrying capacity of the component. The initial imperfection reduced the member capacity by 6.3% to 12.7%. (2)The web openings will affect the failure mode of flexural members with H-shaped web openings. When the opening ratio is 0.7, the bearing capacity of the test specimen decreases by 31.2%–47.1%. The local buckling of the flange and web occurs at the same time as the failure of the vierendeel mechanism. (3) The bearing capacity of narrow flange members can be reduced by 2.3 times as much as that of wide flange members. The greater the section width to height ratio, the greater the ultimate bearing capacity of the member. (4) The finite element method and theoretical formula proposed in this paper can better simulate the bearing capacity and failure mode of H-shaped aluminium alloy members with web openings under bending.