A variable capacity compressor and a starting method thereof. The variable capacity compressor includes a four-way valve having a suction gas distribution function and an idling chamber high-pressure injection function, thereby achieving a reduced manufacturing cost and an improved reliability incurred by the use of a validated component. Further, a boosting algorithm is applicable to obtain a driving source of the four-way valve in an initial parallel pressure state. In the variable capacity compressor comprising a plurality of compression chambers having different capacities and a four-way valve to distribute a suction refrigerant gas into the plurality of compression chambers, a starting method thereof comprises determining whether the variable capacity compressor is in an initial starting mode, and controlling the four-way valve to generate a pressure difference among the plurality of compression chambers to move a piston of the four-way valve from an initial parallel pressure state if the variable capacity compressor is determined to be in the initial starting mode.