The utility model discloses a coal gasification slag collecting device. The screening device comprises a vibration device, a screening hopper, a supporting frame, a storage tank and a heat exchange pipe. a vibration device is mounted at the inner bottom of the support frame; four groups of damping springs are mounted at the top of the vibration device; a screening hopper is mounted at the tops ofthe damping springs; a first discharging pipe, a second discharging pipe and a third discharging pipe are sequentially mounted on one side of the screening hopper from bottom to top; a first control switch, a second control switch and a third control switch are sequentially installed at the positions, close to the discharging port, of the first discharging pipe, the second discharging pipe and thethird discharging pipe. a shell is mounted at the top of the supporting frame; due to the fact that the vibrating device and the screening hopper are arranged, slag enters the screening hopper to bescreened after being cooled and is classified according to the diameter of the slag, the slag is convenient to use next time, and the situation that a large amount of time, manpower and material resources are wasted due to the fact that the slag needs to be independently screened next time is avoided.