The invention discloses a floor beam mounting bracket and a using construction method. According to the floor beam mounting bracket and the using construction method, the floor beam mounting bracket comprises a bracket body, the top of the bracket body is provided with a crossbeam used for supporting a floor beam and a height adjusting mechanism used for adjusting the height of the crossbeam, andthe crossbeam is provided with a transverse adjusting plate and a transverse adjusting mechanism driving the transverse adjusting plate to move in the length direction of the crossbeam; longitudinal adjusting mechanisms used for adjusting the position of the floor beam in the width direction of the crossbeam are arranged at the two ends or the positions close to the two ends of the transverse adjusting plate in the length direction. According to the mounting bracket, the horizontal position, the angle and the height of the floor beam can be adjusted accurately, the occupancy time of a tower crane and adjustment requirements, for the position of the floor beam, of the tower crane are reduced effectively, and the construction quality of the floor beam is greatly improved on the basis.