Abstract: According to the hypoxia phenomenon occurred in mining process of No.22306 fully-mechanized coal mining face in Bulianta Mine ,the paper studied the ca uses of hypoxia occurred.According to the measurements,the hypoxia scope could be divided into three areas of hypoxia area at air returning corner,hypoxia area at the tai I of the scraper conveyor and hypoxia area at the coal mining face.With the study and analysis conducted,gas deposited at CO2~ N2 zone,a shallow depth mining,mine neg ative pressure ventilation,ultra large area goaf and the influences from the surface atmospheric pressure variation would be the causes of hypoxia occurred.Based on the ci rcumstances,the measures of leakage sealing at the mine surface ground and underground,ventilation guided with air curtain,air dilution with pneumatic fan,borehole press ure released,pressure balanced ventilation and other comprehensive hypoxia prevention and control were conducted. The results showed that the above measures conduc ed could effectively control hypoxia.The coal mining face with U type pressure balanced ventilation would cause hypoxia at air returning corner,when the atmospheric press ure was dropped by 700 Pa.Hypoxia would be occurred at the tail of scraper conveyor when the atmospheric pressure was dropped by 900 Pa.Hypoxia would occur at 40 m of coal mining face to air returning corner when the atmospheric pressure was dropped by 1 020 Pa.When Y type pressure balanced ventilation was applied to coal minin g face,the atmospheric pressure varied would have less influences to the oxygen variation in coal mining face.