The invention relates to a constant-pressure roller which is characterized by comprising a longitudinal center shaft, wherein an annular center airbag is disposed on the circumferential outer side of the center shaft; the circumferential outer side of the center airbag is in a sleeved connection with a fixation tube; 20 sub-airbags are distributed uniformly on the circumferential outer side of the fixation tube; 20 radial communicating tubes are disposed on the fixation tube; the 20 sub-airbags communicate with the center airbag by the communicating tubes respectively; and 20 radial rubber baffles are distributed uniformly on the circumferential outer side of the fixation tube, and every two adjacent sub-airbags are separated by one of the rubber baffles. The roller provided by the invention is characterized in that a rubber outer tube is supported by the center airbag and the sub-airbags, so that the roller surface has very high elasticity; through regulation of air pressures of the center airbag, the temperature and pressure of the rubber outer tube on the roller surface can be kept, constant-pressure operations of the roller can be ensured, and optimal operational efficiency of the roller can be guaranteed; and because of the multi-layer roller structure, the roller is provided with high structural strength and good elastic buffer space, and operational requirements in different operational environments can be satisfied.