A parking guidance system and method and an automatic parking system. The method includes: detecting corners of a marked parking space; planning a vehicle's parking path based on the corners; and providing parking guidance based on the parking path. The planned parking path includes: a first straight path the vehicle will travel straight to a first turning point; a first turning path the vehicle will turn a first angle from the first turning point along the circumference of a first turning circle; a second straight path the vehicle will travel from the end point of the first turning path to a second turning point; a second turning path the vehicle will turn a second angle from the second turning point along the circumference of a second turning circle; and an intra-parking-space path the vehicle will travel from the end point of the second turning point to a stop point.