A system for acquiring a rotor position of a rotary transformer, comprising: a rotary transformer decoder, a low pass filter and a microprocessor, wherein the microprocessor comprises a synchronous demodulation module and a calculation module, the rotary transformer decoder is electrically connected to the rotary transformer through the low pass filter, and is configured to output an excitation signal to drive the rotary transformer and acquire first position information of the motor rotor, the first position information comprising at least a first rotor position and a first rotor speed, the synchronous demodulation module is electrically connected to the rotary transformer decoder and the rotary transformer, and is configured to collect at least a rotary transformer cosine signal and a rotary transformer sinusoidal signal outputted from the rotary transformer and output a feedback signal, the feedback signal comprising at least a target rotary transformer sinusoidal signal and a target rotary transformer cosine signal, the calculation module is connected to the synchronous demodulation module, and is configured to perform calculation to acquire second position information of the motor rotor based on the feedback signal and according to a preset algorithm, the second position information comprising at least a second rotor position and a second rotor speed; characterized in that, the synchronous demodulation module comprises: a first analog-to-digital conversion module, a first low pass filter (FIR LPF), and a first data decimation module, the first analog-to-digital conversion module is configured to acquire a first excitation signal with a phase delay of a first preset value obtained based on the excitation signal from the rotary transformer decoder, a first rotary transformer sinusoidal signal and a first rotary transformer cosine signal with a phase delay of a second preset value obtained based on the rotary transformer sinusoidal signal and the rotary transformer cosine signal respectively, output a first digitalized excitation signal, a first digitalized rotary transformer sinusoidal signal, and a first digitalized rotary transformer cosine signal, wherein calculation is performed based on the first digitalized excitation signal, the first digitalized rotating sinusoidal signal, and the first digitalized rotating cosine signal, to acquire a first signal and a second signal, the first low pass filter is configured to filter the first signal and the second signal to acquire a first filtered signal and a second filtered signal, and the first data decimation module is configured perform data decimation on the first filtered signal and the second filtered signal to acquire the target rotary transformer sinusoidal signal and the target rotary transformer cosine signal, respectively. the microprocessor comprises a synchronous demodulation module and a calculation module, the rotary transformer decoder is electrically connected to the rotary transformer through the low pass filter, and is configured to output an excitation signal to drive the rotary transformer and acquire first position information of the motor rotor, the first position information comprising at least a first rotor position and a first rotor speed, the synchronous demodulation module is electrically connected to the rotary transformer decoder and the rotary transformer, and is configured to collect at least a rotary transformer cosine signal and a rotary transformer sinusoidal signal outputted from the rotary transformer and output a feedback signal, the feedback signal comprising at least a target rotary transformer sinusoidal signal and a target rotary transformer cosine signal, the calculation module is connected to the synchronous demodulation module, and is configured to perform calculation to acquire second position information of the motor rotor based on the feedback signal and according to a preset algorithm, the second position information comprising at least a second rotor position and a second rotor speed; characterized in that, the synchronous demodulation module comprises: a first analog-to-digital conversion module, a first low pass filter (FIR LPF), and a first data decimation module, the first analog-to-digital conversion module is configured to acquire a first excitation signal with a phase delay of a first preset value obtained based on the excitation signal from the rotary transformer decoder, a first rotary transformer sinusoidal signal and a first rotary transformer cosine signal with a phase delay of a second preset value obtained based on the rotary transformer sinusoidal signal and the rotary transformer cosine signal respectively, output a first digitalized excitation signal, a first digitalized rotary transformer sinusoidal signal, and a first digitalized rotary transformer cosine signal, wherein calculation is performed based on the first digitalized excitation signal, the first digitalized rotating sinusoidal signal, and the first digitalized rotating cosine signal, to acquire a first signal and a second signal, the first low pass filter is configured to filter the first signal and the second signal to acquire a first filtered signal and a second filtered signal, and the first data decimation module is configured perform data decimation on the first filtered signal and the second filtered signal to acquire the target rotary transformer sinusoidal signal and the target rotary transformer cosine signal, respectively.