The invention relates to a polyester-mixed cotton cloth mercerizing machine and a mercerizing process. The mercerizing machine comprises a rack, wherein a first removing mechanism is arranged on the rack, and the first removing mechanism comprises a spraying box, a spraying device and a driving device; and the spraying box is arranged on the rack and contains cleaning liquid, the spraying device is arranged on the spraying box and sprays cloth, the spraying device comprises a spraying pump and a spraying pipe, the spraying pump is arranged on the spraying box, the spraying pipe is arranged onthe spraying box, a pipe opening of the spraying pipe faces the cloth, the driving device is arranged on the spraying box, the driving device comprises a driving roller and a driving piece, the driving roller is rotatably arranged on the spraying box and abuts against the cloth, and the driving piece is arranged on the spraying box and connected with the driving roller. The spraying pump is started to enable the cleaning liquid to be sprayed onto the cloth, so that alkali liquor on the cloth is cleaned up, the content of the alkali liquor when the cloth enters the next procedure is reduced, the influence of the alkali liquor on the next procedure is reduced, and the quality of the cloth is improved.