Abstract: In this study,the feasibility of quartz reverse flotation by depressing lignite using low-temperature air plasma pre-treatment was investigated. SEM,EDS,XPS and contact angle were carried out to measure the surface property of pure quartz before and after plasma treatment. SEM detected the new product of 1-5 μm metal silicate mineral grains on the quartz surface after plasma treatment,but the surface change was little. XPS results show that the content of C—C / C—H groups decreased gradually,and the content of C—O group increased. However,the contents of C O and COO groups did not change. The contact angle and flotation test results indicate that the difference of contact angle be- tween quartz and lignite treated for 1-5 minutes increased by 2. 5-3. 2 times. The rate of quartz floatation was almost constant when treated with flotation alone,and the rate of lignite was significantly reduced. At the time of mixed flota- tion,the plasma pretreatment was used to obtain the good index of 8. 32% of concentrate ash and 37. 8% of yield. The plasma modification significantly expanded the difference between quartz and lignite,and it was feasible to inhibit the reverse flotation of lignite.