The invention discloses a powder leakage monitoring device and a powder leakage monitoring method. The powder leakage monitoring device comprises light field camera, 3D PTZ (3-Dimensional Pan/Tilt/Zoom) and computer. Wherein, the light field camera records original light field images of monitored area; the 3D PTZ under the light field camera adjusts the shooting angle of the light field camera when it rotates according to the set direction; and the computer respectively connects to the light field camera and the 3D PTZ, which generates refocused images corresponding to the original light field images, and determines the spatial coordinates of the powder leakage point and the hazard range of the powder leakage in the monitored area according to the refocused images and the shooting angle. Therefore, the range and accuracy of powder leakage monitoring are both increased by using this invention.