The invention provides a hot in-place recycling ultrathin overlaying machine of a bituminous pavement and a construction method thereof. The hot in-place recycling ultrathin overlaying machine of the bituminous pavement comprises an automobile chassis, an integral power device, an electric control system, a diesel tank, a receiving and transporting device, a material transfer hopper, a horizontal transporting device, a heating device, a hydraulic system, a recycling agent spraying system, a harrowing device, a distributing spiral device, a paving screed device, a cab, and an electric control operating floor, wherein the automobile chassis is a special automobile chassis. The hot in-place recycling ultrathin overlaying machine of the bituminous pavement finishes the continuous overlay repair work of the pavement through a series of processes such as receiving the materials, feeding the materials quantitatively, transporting the materials horizontally, spraying the recycling agent, harrowing, heating, distributing and paving the materials, ironing, and grinding and the like, and has the advantage of carrying out one-time maintenance on the defects such as loose, shallow vertical and horizontal cracks, track, slight crack, bituminous aging, pavement seepage and the like of a functional layer of the pavement. By adopting the invention, the antiskid resistance of the pavement is restored, the profile of the pavement is corrected, the appearance and the evenness of the pavement are improved, the pavement strength of the pavement is increased, the traffic noise is reduced, and the service life of the pavement is prolonged.