The invention discloses a degreasing-free on-line water removal device for wet temper-rolling of metal plate strips. The plate strips are rolled to be flat through a roller. The on-line water removal device comprises a uniform tempering lubricant spraying mechanism (20), one or more blowing mechanisms (30) and one or more hot air drying mechanisms (40), wherein the uniform tempering lubricant spraying mechanism (20) is arranged on one or more sides of the metal plate strips at the upstream position of the roller, the blowing mechanisms (30) are arranged on one or more sides of the metal plate strips at the downstream position of the roller, and the hot air drying mechanisms (40) are arranged at the downstream positions of the blowing mechanisms (30). According to the on-line water removal device for wet temper-rolling, metal steel belts do not need to be treated on a degreasing line and can be directly drawn and straightened without being degreased, the plate surfaces are clean, chromatic aberration and pits are avoided, and the roller consumption is lowered.