The invention relates to a variable displacement swash plate compressor. A swash plate driving mechanisms with a flexible driving balance design is provided, has proper flexibility during work, overcomes unbalanced force and moment acting on the swash plate, improves vibration, noise, kinematic pair blockage and excessive wear caused by the unbalanced force and moment, and reduces machining and assembly precision of related workpieces; a piston with a spiral linear oil groove is provided and stores oil, and through the reciprocation of the piston and the acceleration change of the piston, lubricating oil flows reasonably between the kinematic pair and is uniformly distributed on the cylindrical surface of the piston and the peripheral surface of the cylinder to improve the sealing and lubricating properties between the piston and the peripheral surface of the cylinder, improve the performance of the compressor and prolong the service life of the piston; and a cylinder cover capable ofbeing formed at one time through die casting and having simple process is provided, and suction and discharge channels adopt a single-section or multi-section expansion chamber-type cavity consistingof alternate contraction sections and expansion sections to improve the vibration and air flow noise caused by suction and discharge pulsation.