The invention discloses an asynchronous motor frequency converter device with low-voltage ride through capability. An alternating-direct-alternating mode is adopted for a frequency converter, namely, firstly converting a working frequency alternating power supply into a direct current power supply by a rectifier; and then converting the direct current power supply into an alternating power supplywith controllable voltage and frequency through an inversion link and providing the alternating power supply to an asynchronous motor. A diode rectification module in the inner part is switched in after the working frequency alternating power supply is switched in the frequency converter; the alternating current is converted into direct current; the output of a rectifier bridge is switched into aBOOST module; the output of the BOOST module is switched into the input of a DC/AC (direct current/alternating current) inverter module; and the output of the inverter module, serving as an alternating current supply, is directly supplied to the asynchronous motor. Under the normal condition, the BOOST module is not started, when the drop of the power grid voltage is detected, the BOOST module starts automatically, sufficient direct current voltage sources for the inversion link are ensured, and the stable operation of the asynchronous motor is ensured.