The invention provides a digital 
mammary gland X-
ray machine and an automatic 
exposure image optimization method thereof.The digital 
mammary gland X-
ray machine comprises a 
mammary gland X-
ray machine base, a spherical 
pipe support, a spherical 
pipe, a mammary gland beam 
limiter, a stepping motor, a lead screw, a 
potentiometer, a lead screw nut, a 
pressure sensor, a compressor and a breast supporting frame.The spherical 
pipe is arranged on the top of the spherical 
pipe support.The mammary gland beam 
limiter is arranged on the spherical 
pipe support, located below the spherical pipe and used for filtering out hard rays or soft rays in X rays emitted by the spherical pipe and prompting the 
irradiation range of X rays.The stepping motor is arranged on the mammary gland X-ray machine base.The lead screw is connected with the stepping motor.The lead screw nut is arranged on the lead screw.The 
pressure sensor is connected with the lead screw nut.The compressor is connected with the 
pressure sensor.The breast supporting frame is located below the compressor.After the mammary gland type is determined, hard rays or soft rays in 
X ray are filtered out through the mammary gland beam 
limiter so that the penetrating force of remaining X rays can be changed, and it can be guaranteed that an optimal image is acquired and the 
radiation dosage a patient suffering from can be reduced.