The present invention discloses a transformer arcless on-load tap switch. The transformer arcless on-load tap switch comprises a control loop, a moving contact and a static contact. The main contact and the first transition contact of the moving contact are connected with a current static contact in a steady state operation, and the main contact is configured to conduct current; when a switching motion is executed, the main contact is disconnected after a first two-way switch is triggered in advance; the control loop is configured to determine whether the terminal voltage of each two-way switch is drop voltage or grade winding voltage or not and switch each transition branch according to the determination result; and the transition branch of a second two-way switch is stopped to trigger after the main contact and a second transition contact are overlapped to the next static contact, and the main contact is configured to conduct current. According to the invention, a circuit is taken as a transition branch, and the switching of the circuit is controlled according to the change condition of the terminal voltage of each two-way switch, so that the switching loss and switching cost are reduced while the switching arcless is realized.