The invention discloses a high-sensitivity alpha 
energy spectrum measuring method of 
radon concentration in air by using a 
radon and 
daughter collecting device, an alpha 
ray semi-conductive 
detector, a temperature and 
humidity measuring module, a circuit 
system, a man-computer interface and a 
computer data analysis system. The sensitivity surface of the alpha 
ray semi-conductive 
detector is arranged in a cavity of the 
radon and 
daughter collecting device, and the alpha 
ray semi-conductive 
detector, the temperature and 
humidity measuring module and the man-computer interface are connected with the circuit 
system which is connected with the 
computer data analysis system through a 
USB (Universal Serial 
Bus) interface. The method collects radon in the air by adopting a static 
diffusion mode, absorbs radon charged daughters by adopting a high-pressure electrostatic mode, distinguishes radon-
thorium daughters by utilizing the alpha ray semi-conductive detector to measure air radon concentration through alpha 
energy spectrum measurement and correct influence on the measurement of radon concentration by adopting a temperature-
humidity synchronous measuring mode. The method is suitable for the fields of monitoring radon level and controlling 
pollution in the indoor 
radiation environment of civil constructional 
engineering, monitoring radon concentration in mines and tunnels, and the like.