The invention relates to an open winding type permanent magnet motor driven reconstructed vehicle-mounted charging system for an electric vehicle. The system comprises a single-phase AC power supply,a rectifier bridge, an input filtering capacitor, three-phase voltage inverters, a three-phase permanent magnet motor winding, an output filtering capacitor, a storage battery and mode switches. The charging system sufficiently utilizes original double three-phase inverters, the permanent magnet motor winding, control and sensor units and the like of electric vehicles, and total integration of functions such as motor driving, high-power factor charging, harmonic control and the like is realized by optimizing topology to complete rectification, inversion and power factor correction. During charging, two three-phase voltage inverters are reconstructed into a three-phase cascading Buck-Boost circuit; the permanent magnet motor winding serves as an energy storage inductor of the three-phase cascading Buck-Boost circuit. By means of the charging system, the cost of a device can be effectively reduced and high-power factor charging can be realized.