The utility model discloses a rubber belt conveyor stores up cassette holder combination formula and prevents centring device, wherein, the device is including unable adjustment base and belt hold roller, and the belt hold roller is fixed on unable adjustment base, unable adjustment base with store up cassette holder frame fixed connection, two -way spacing in the left and right sides of belt realization level and vertical direction is installed to the belt hold roller. The utility model discloses a belt hold roller of setting in belt both sides carries on two -way spacingly to the belt, can firmly restrict the belt position, prevents the belt off tracking, and the belt hold roller can be along with belt operation carrying on flexible rotation, against abrasion belt simultaneously. The stability of the off tracking effect is prevented to the belt in storing up the cassette holder, prevent to store up in the cassette holder belt scurry move, the turnup, avoid damaging the belt, prevent the centring device, the sealing -tape machine operation is improved.