The invention discloses a rotary compressor which comprises a shell and a compression mechanism. The compression mechanism is arranged in the shell and comprises an air cylinder assembly and a crankshaft. The air cylinder assembly comprises at least one air cylinder. Each air cylinder is provided with an air cylinder cavity. A piston is arranged in each air cylinder cavity. The crankshaft penetrates the air cylinder assembly and comprises a crankshaft body and at least one eccentric part arranged on the crankshaft body. Each eccentric part is sleeved with the corresponding piston. A sliding piece groove is formed in each air cylinder. A radial clearance between the outer circumferential wall of each piston and the inner circumferential wall of the air cylinder cavity corresponding to the piston is delta, when the angle that each eccentric part rotates from the center axis of the corresponding siding piece groove in the operation direction of the rotary compressor is theta, delta has the minimum value delta min, and theta meets the condition that 280 degrees<=theta<=340 degrees. According to the rotary compressor, the minimum radial clearance delta min can be set to be smaller, friction losses are reduced, the refrigerating capacity is improved, and the performance and reliability of the rotary compressor are greatly improved.