The invention discloses a cutting device for machinery manufacturing and a cutting method. The cutting device comprises a cutting table, a support plate and vibration reduction springs, wherein a steel plate is arranged on the cutting table; strip-shaped through holes are formed in the steel plate; a slide groove is formed in the front side of the strip-shaped through holes; slide blocks are arranged on the slide groove; a return spring is arranged inside each slide block; a compression block is connected under each return spring; the support plate is positioned above the cutting table; hollowgrooves are formed in the support plate; a motor is arranged at the back side of each hollow groove; the front end of each motor is connected with a rotating shaft; threaded holes are formed in the rotating shaft; and a fixing ring is arranged at the outer side of the threaded hole. Scale lines, the threaded holes and the fixing rings are arranged on the cutting device for machinery manufacturing; the space between cutting blades can be conveniently regulated so as to adapt to the cutting dimension required by different plates; the structure is simple; workers can conveniently perform practical operation; and the convenience of the device is improved.