The invention provides a compressor, which comprises a shell, a crank shaft arranged in the shell, a motor stator, a motor rotor, an upper flange, a lower flange and a compression mechanism between the upper flange and the lower flange. The compression mechanism includes a first stage compression mechanism comprising a first cylinder, a second stage compression mechanism arranged in the downstream of the first stage compression mechanism and including a second cylinder and a third cylinder in parallel; and the displacement of the first cylinder is greater than or equal to that of the second cylinder and the third cylinder. According to the compressor of the present invention the second cylinder and the third cylinder are combined into the second stage compression mechanism Under the same cylinder diameter, so as to increase the displacement of the double stage compressor, widen the displacement range of double stage compressor under existing cylinder diameter, and improve the performance and the heating capacity of the compressor.