The invention discloses a sediment removal machine for removing sediment at the bottom of a pile and a working method thereof. The sediment removal machine comprises a sediment removal device and a main controller for controlling work of the sediment removal device. The sediment removal device comprises an outer cover, a sediment suction tube for sucking the sediment is arranged in the outer cover, and the bottom end of the sediment suction tube extends out of the outer cover so that the sediment at the bottom of the pile can be sucked into the outer cover. At least one layer of sediment filter screen is arranged between the outer cover and the sediment suction tube. The positions where the sediment filter screens are located are lower than an outlet of the sediment suction tube. A water outlet is formed in the bottom surface of the outer cover so as to discharge return mud flowing down the sediment filter screens. A sediment amount sensor is arranged on the upper portion of the inner side face of the outer cover and connected with the main controller. Mud displacement does not exist, mud pouring is not needed, the automation degree is high, operability is high, the sediment removal efficiency and effect are improved, the hole collapse risk caused by mud displacement is avoided, and the problem that the environment is polluted because a large amount of mud is used is solved.