Abstract: According to the development and hydrogeology characteristics of Ordovician limestone in Tangshan mine, this paper evaluated the safety of mining under pressure in the study area in combination with secure hydraulic head, water bursting coefficient and thickness of safety layers. The results showed that Ordovician limestone water level in minefield increased in order from north to south with a small hydraulic slope, the level in study area is the highest and water level elevation is-10~-9 m. The safety hydraulic head value and thickness of safety layers in excavation roadway showed that there were no danger for mining under pressure. The water inrush coefficient showed that there was danger during mining under pressure in the study area at different degree. Attention should be payed to prevent the danger during mining under pressure in some areas while mining 14th coal seam.