Disclosed is a compressor, including a crankshaft (10), and a first cylinder (20), a second cylinder (30) and a third cylinder (40) arranged sequentially in an axial direction of the crankshaft (10). The first cylinder (20) is a high-pressure cylinder, and the second cylinder (30) and the third cylinder (40) are low-pressure cylinders. The compressor also comprises a capacity variation switching mechanism (50) for controlling loading and unloading of the third cylinder (40). The compressor has a full operation mode and a partial operation mode. By means of the capacity variation switching mechanism (50) provided in the compressor, at least one cylinder is allowed to be put into use or unloaded under the action of the capacity variation switching mechanism (50), thus enabling a capacity variation switching function of the compressor to meet operational requirements of different operating conditions.