The invention discloses an electronic cam for a cold header transmission system. A sliding block is connected with a servo motor through a crankshaft; a rotary encoder for collecting a rotation angle of the crankshaft is arranged on a spindle of the servo motor and is in signal connection with a controller; and the controller is connected with the servo motor and an execution unit for processing a part through a servo driver. The invention also discloses a controlling method of the cold header transmission system. The controlling method comprises the following steps: a user inputs a processing curve of the part to be processed and relevant parameters of the part through a human-computer interaction interface; the controller calculates an acceleration and deceleration curve of the sliding block and outputs a control pulse to the servo motor; the servo motor controls the sliding block to run through the crankshaft; the rotary encoder collects the rotation angle of the crankshaft and sends the rotation angle of the crankshaft to the controller; and the controller calculates the running speed and the displacement of the sliding block according to the rotation angle of the crankshaft, outputs a control signal according to the relevant parameters of the part to be processed and controls the motion of the execution unit. The electronic cam and the controlling method can improve the controlling accuracy of the sliding block, reduce noise and save the energy.