A control system for a permanent magnet synchronous traction and transmission system, for controlling of the permanent magnet synchronous traction and transmission system, wherein the control system comprises a sampling unit and a controller; the sampling unit is connected to a permanent magnet synchronous motor, and comprises: a current sensor for collecting an operation excitation current and an operation torque current of the permanent magnet synchronous motor, a voltage sensor for collecting an input capacitor voltage of the permanent magnet synchronous motor, and a resolver for collecting an initial rotor position and a rotor frequency of the permanent magnet synchronous motor; the controller comprises: an instruction acquisition unit, configured to acquire a target torque instruction issued to the traction and transmission system; a Maximum Torque Per Ampere (MTPA) calculation unit, configured to calculate a target excitation current value and a target torque current value according to the target torque instruction; a regulation unit, comprising: an excitation regulation unit and a torque regulation unit; the excitation regulation unit configured to generate an excitation current regulation value according to the target excitation current value and an operation excitation current value; and the torque regulation unit configured to generate a torque current regulation value according to the target torque current value and an operation torque current value; a decoupling control unit, configured to generate a target modulation ratio and a modulation frequency according to the excitation current regulation value and the torque current regulation value output from the regulation uni t; and a segment synchronous modulation unit, configured to output a Pulse Width Modulation modulation wave control signal for the permanent magnet synchronous motor, according to the target modulation ratio and the modulation frequency generated by the decoupling control unit; a flux-weakening compensation unit, configured to generate compensation signals for the target excitation current value and the target torque current value to compensate for both; characterized in that, the flux-weakening compensation control unit converting a converted input capacitor voltage according to a set target modulation ratio; after a comparison with the input capacitor voltage acquired by sampling, generating a torque current compensation amount and an excitation current compensation amount by regulation, and outputting the torque current compensation amount and the excitation current compensation amount to a current accurate calculation unit to add with the target torque current value and the target excitation current value calculated by the MTPA calculation unit for synthesis, so as to perform the accurate current calculation an instruction acquisition unit, configured to acquire a target torque instruction issued to the traction and transmission system; a Maximum Torque Per Ampere (MTPA) calculation unit, configured to calculate a target excitation current value and a target torque current value according to the target torque instruction; a regulation unit, comprising: an excitation regulation unit and a torque regulation unit; the excitation regulation unit configured to generate an excitation current regulation value according to the target excitation current value and an operation excitation current value; and the torque regulation unit configured to generate a torque current regulation value according to the target torque current value and an operation torque current value; a decoupling control unit, configured to generate a target modulation ratio and a modulation frequency according to the excitation current regulation value and the torque current regulation value output from the regulation uni t; and a segment synchronous modulation unit, configured to output a Pulse Width Modulation modulation wave control signal for the permanent magnet synchronous motor, according to the target modulation ratio and the modulation frequency generated by the decoupling control unit; a flux-weakening compensation unit, configured to generate compensation signals for the target excitation current value and the target torque current value to compensate for both; characterized in that, the flux-weakening compensation control unit converting a converted input capacitor voltage according to a set target modulation ratio; after a comparison with the input capacitor voltage acquired by sampling, generating a torque current compensation amount and an excitation current compensation amount by regulation, and outputting the torque current compensation amount and the excitation current compensation amount to a current accurate calculation unit to add with the target torque current value and the target excitation current value calculated by the MTPA calculation unit for synthesis, so as to perform the accurate current calculation