Abstract: Using 20 Lnearly spherical explosion characteristic test system, studied the change laws of explosion limits under gas and coal dust coexisting conditions. The study found that:under the experimental conditions, coal dust lower explosion limit decreases with the increase of the gas concentration, pure coal dust lower explosion limit is 28.4g/m³, while adding 1.70% gas its lower explosion limit down to 7.8g/m³, coal dust lower explosion limit and gas concentration are exponential relationship; gas upper explosion limit alters with the increase of the coal dust concentration, pure gas upper explosion limit is 15.8%, while adding 100g/m³ dust its upper explosion limit down to 12.8%; gas lower explosion limit decreases with the increase of the coal dust concentration, pure gas lower explosion limit is 5.10%, while adding 100g/m³ dust its lower explosion limit down to 3.10%; gas upper explosion limit and lower explosion limit were exponential function relationship with coal dust concentration. The study results provided a theoretical basis for the prevention and control of coal mine gas and coal dust explosion accidents.