Abstract: Existing research results show that under the action of high temperature in a fire, the steel beam web and lower flange near the first hole at the beam end of the honeycomb composite beam will buckle significantly. It conducts a constant load temperature rise test and numerical simulation analysis on the honeycomb composite beam without opening within a certain length at the beam end, considering the effects of different beam end restraints, opening ratio, the distance between the first hole and the beam end, width-to-thickness ratio of the flange, and height-to-thickness ratio of the web on the fire resistance of the partially open honeycomb composite beam. The research shows that local openings improve the buckling behavior of the web and lower flange at the beam end of the honeycomb composite beam under a fire, and enhance the fire resistance of the honeycomb composite beam; due to the existence of beam end restraint and temperature gradient, in the early stage of temperature rise, the vertical deformation of the rigid-connected composite beam at the beam end appears to be a reverse arche, and the vertical deformation of the hinged composite beam at the beam end appears to be a platform section. Throughout the process of temperature rise and fall, the concrete flange undergoes complex cracks; through the analysis of simulation results, it is concluded that when the distance between the first hole of the honeycomb composite beam and the beam end is 4 times the hole diameter, and the height-to-thickness ratio of the web is 40.75, the fire resistance is most improved.