In order to study the influence factors of the control system and structure of the rotor on the thermal bow vibration in magnetic bearings-rotor system， a new method is proposed based on its thermal bending vibration mechanism to constantly update the calculation conditions， iterative calculation， until the vibration convergence or divergence. So， the influence of the electric control parameters and the rotor structure parameters on thermal bending vibration is obtained. The calculation results show that， among the electronic control parameters， changing the bias current and integral coefficient has no obvious influence on the thermal bending vibration， while increasing the proportional coefficient and differential coefficient can increase the influence of the thermal bending vibration. In terms of rotor structure parameters， increasing the length of the non-cantilever and cantilever lateral axis reduces the influence of thermal bending vibration， while increasing the cantilever length and the radius of the external disk slightly increases the influence of thermal bending vibration. It can be seen that the amplitude-frequency characteristics of the electronic control system and the rotor itself determine the influence degree of thermal bending， and the phase-frequency characteristics of the two determine the change trend of thermal bending vibration.