A control method and system for a resonant linear compressor applied for controlling the capacity of a cooling system. The method includes: a) reading a reference operation power (Pref) of the motor of the compressor; b) measuring an operation current (iMED); c) measuring an operation voltage of a control module of the compressor; d) calculating an input power (PMED) of the motor as a function of the operation current (iMED) and of the operation voltage; e) comparing the input power (PMED) with the reference operation power (Pref); f) if the reference operation power (Pref) is higher than the input power (PMED), then increase an operation voltage of the compressor (UC); g) if the reference operation power (Pref) is lower than the input power (PMED), then decrease the operation voltage of the compressor (UC).