Excavating machine

The invention relates to an excavating machine which aims at overcoming the defect that the operation radius is small due to the fact that the upper portion rotating structure of the existing excavating machine can only rotate around the rotary center of the upper portion rotating structure. The excavating machine comprises a lower portion mechanism for travelling and an upper portion mechanism; the upper portion mechanism comprises a rotary platform, a working device, a control chamber, a power system and a hydraulic system, wherein the working device, the control chamber, the power system and the hydraulic system are arranged on the rotary platform; the working device is driven by the power system to move through the hydraulic system; the lower portion mechanism is provided with a sliding platform which can move longitudinally on the lower portion mechanism; the rotary platform is arranged on the sliding platform. According to the excavating machine, the lower portion mechanism is responsible for the complete machine movement, the upper portion mechanism can be driven by the sliding platform to move on the lower portion mechanism, meanwhile the rotary movement of the upper portion mechanism can be performed on the sliding platform, and accordingly the operation radius of the excavating machine can be large under the condition that the lower portion mechanism does not move.