An electromagnetic pen, an electromagnetic signal transmission method and an electromagnetic signal processing method, a processing device and a processing apparatus comprises: a reference inductance and a reference capacitor, connected with each other in parallel in a housing of the electromagnetic pen and configured to transmit an electromagnetic signal in a handwritten frequency; a control capacitor, connected with the reference capacitor in parallel and controlled by a control switch connected in series so as to transmit an electromagnetic signal in a control frequency. The processing device comprises: a receiving identification module, configured to receive the electromagnetic signal transmitted by the electromagnetic pen and identify a frequency of the electromagnetic signal; a handwritten input module, configured to input a handwritten symbol when the identified frequency is within a range of the handwritten frequency; and a control input module, configured to input a control signal.