The invention discloses a transformer substation indoor detecting robot with a linear motor and a method. The transformer substation indoor detecting robot comprises a robot body and a truss system. The truss system comprises a first direction truss and a second direction truss which have the adjustable opposite positions. The robot body comprises a base horizontal rotating mechanism, multi-stagemechanical arms connected with the base horizontal rotating mechanism, a cradle head arranged at the tail ends of the multi-stage mechanical arms and adjustable in posture between the multi-stage mechanical arms, and detecting equipment carried on the cradle head. Through relative movement of the first direction truss and the second direction truss and multiple adjustment of postures among the multi-stage mechanical arm, the detecting equipment and the multi-stage mechanical arm of the robot body, the detecting robot can move to any point in a coordinate of the indoor space of a transformer substation.