To meet the particular safety requirements for underground coal mining, this paper proposes is going to investigate the capability of ultra-fine fly ash (UFA) with styrene-acrylic emulsion to improve safety for underground mine workers. After studying on the influence of different percentages of UFA on the comprehensive property of seal coating, the optimal amount of UFA is determined as 60%. The water absorption of the seal coating after 7 d is 5.0%. Its original tensile strength is 3.09 MPa. The elongation at break is 80%, and the bonding strength is 0.72 MPa (7 d) and 1.08 MPa (14 d), up to the level II standard of GB/T23445-2009 polymer cement water proof coating. The flame retardant property and antistatic property is up to the safety standard for gas-sealing materials of underground coal mine of MT113-1995. Scanning electron microscopy and air tightness tests show that this material has a compact pore structure with good air tightness, and can be used as gas seal coating for underground coal mine. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.