A system of a robot for human following includes the robot faced toward a first direction. The robot includes a detecting device, a controlling device and a mobile device. The detecting device detects a target human and a obstacle. The controlling device generates a first parameter according to a first vector between the target human and the robot, generates a second parameter according to a second vector between the obstacle and the robot, and generates a driving command according to a first resultant force parameter generated from the first parameter and the second parameter and an angle value between the first direction and the first vector to drive the robot. The mobile device performs the driving command to enable the robot dodging the at least one obstacle and following the target human, simultaneously. A controlling method of a robot for human following is also disclosed herein.