Controlling method for air cylinder volume changing of linear compressor

The invention provides a controlling method for air cylinder volume changing of a linear compressor. The linear compressor comprises a shell, a stator, a main coil, a piston, an air cylinder, a rotor, a spring and a rear baffle, wherein the stator, the main coil, the piston, the air cylinder, the rotor, the spring and the rear baffle are arranged in the shell. A permanent magnet is arranged on the rotor. The controlling method for the air cylinder volume changing of the linear compressor is characterized in that the rotor is further provided with a secondary coil, and the secondary coil is used for selectively overlaying or offsetting magnetic field strength generated by the main coil; and the controlling method comprises the first step of detecting an upper dead point and the second step of adjusting the cylinder volume. According to controlling method for the air cylinder volume changing of the linear compressor, efficiency and reliability of the linear compressor are improved.