The invention belongs to the technical field of mechanical loading and unloading equipment, and particularly relates to a negative pressure bulk tank car device. The device comprises a finished product tank, a discharging pipe arranged at the discharging end of the finished product tank, a negative pressure pipe, an exhaust fan, a mounting platform, a lifting device, a telescopic part and a bulk head, wherein the lifting device is arranged on the upper surface of the mounting platform, the lifting device can drive the bulk head to move up and down, the bulk head drives the telescopic part to stretch and retract, the telescopic part and the bulk head are provided with a communicating hollow layer, the hollow layer communicates with one end of the negative pressure pipe, and the other end ofthe negative pressure pipe communicates with the top of the finished product tank. When the negative pressure bulk filling tank device carries out discharging on a carrying vehicle, the lifting device adjusts the position of the bulk head according to an actual height of the carrying vehicle, the dust raising phenomenon can be caused, the bulk head and the telescopic part can be subjected to negative pressure through the exhaust fan, the dust is sucked away and sent back to the interior of the finished product tank to be reused, the dust raising phenomenon is eliminated, the product waste isreduced, the operation efficiency is improved, and the health and environment of workers are protected.