The invention discloses a smoothening device for garment fabrics. The smoothening device comprises a device base, a first dewatering device, a second dewatering device, a device casing, a hydraulic machine, an ironing device, a suction fan, a first feeding roller, a second feeding roller, a third feeding roller, a hot-air blower, a fabric smoothening block and a rolling device. Compared with the prior art, the smoothening device has the advantages that the smoothening device is simple in structure and reasonable in design; through sequential operations including dewatering, ironing, drying, wrinkle removing and rolling of fabrics treated by softeners, wrinkles and folds on the fabrics can be effectively removed to restore the smoothness of the fabrics, so that subsequent processing is facilitated.