The invention discloses a magnetic anti-falling protection device and a magnetic field control method thereof. The device comprises a suspender type safety belt body, a power unit, a control unit provided with a work power source through the power unit, a magnetic field generation unit and a contact state collection unit. The magnetic field generation unit comprises at least four sets of magnetic field generators corresponding to the two hands and the two feet correspondingly and fixing mechanisms capable of fixing the magnetic field generators in gloves or boots. The contact state collection unit comprises at least four position sensors correspondingly arranged on the two hands and the two feet correspondingly. The position sensors collect contact state information between the corresponding portions and a pole tower and transmit the collected information to the control unit. According to the received contact state information, the control unit controls the magnetic field generators to generate a magnetic field used for adsorbing the pole tower or stop generating the magnetic field. According to the magnetic anti-falling protection device and the magnetic field control method thereof, the contact states between the hands and feet and the pole tower can be monitored in real time in the climbing process of a worker, and then falling accidents are avoided by means of magnetic adsorption control.