Embodiments of the invention disclose a servo dead zone compensation method, a device and a system thereof. The method comprises the following steps of acquiring a coefficient a and a coefficient b of an initial formula of a dead zone compensation amount Tcom at N target direct current amounts ia respectively, wherein the N is an integer which is greater than or equal to 10 and the Ts is a carrier wave period of a switch tube of a three-phase inverter; when a frequency load K of the switch tube of the three-phase inverter is a certain value, calculating to acquire a dead zone compensation amount Tcom corresponding to each target direct current amount ia is calculated according to the initial formula, wherein the K equals to 1/Ts; and according to the dead zone compensation amount Tcom corresponding to the target direct current amounts ia, carrying out dead zone compensation on the three-phase inverter. In the embodiments of the invention, an accurate dead zone compensation amount can be acquired so as to further improve a dead zone effect; a torque ripple of a servo system under a low speed is reduced; and low speed performance of the system is increased.