The invention relates to a mixing machine, in particular to a printing ink mixing machine for a printing plant and aims to provide the printing ink mixing machine which can be used for printing under an airtight condition and consumes short time during preparation. The printing ink mixing machine for the printing plant comprises a mixing box and the like, wherein a funnel is connected in the middle of the top of the mixing box; a discharging pipe is connected in the middle of the bottom of the mixing box; a valve is arranged on the discharging pipe; a mixing mechanism is arranged in the mixing box; knocking mechanisms are connected on left and right sides of the mixing box respectively and connected with the mixing mechanism. The mixing mechanism and the knocking mechanisms are arranged to achieve to the purpose of mixing raw materials for preparation of printing ink; a cover plate is arranged and can prevent dust from entering the mixing machine; an insertion rod is inserted into a through hole, so that the cover plate can be fixed; a floodlight performs an illumination function and operation of workers is facilitated.