The invention provides aheight adjustment system and height adjustment method, comprising: a height detecting part arranged on the platform to detect the height of the platform; a height detecting part arranged on the platform to detect the height of the platform. And a height adjusting part provided on the bogie, wherein the height adjusting unit is capable of receiving data of the height of theplatform detected by the height detecting unit and adjusting the height of the carriage according to the data of the height of the platform so that the height of the floor of the carriage coincides with the height of the platform. When the train enters the station, the height detecting section can detect the platform height to obtain the data of the platform height, and the height adjusting section adjusts the height according to the data of the platform height to make the floor height of the carriage consistent with the platform height, so that passengers can get on and off the train conveniently, and the adjustment process is automatic, simple and quick.