Abstract: In view of the steel structure with high strength big hexagonal head tap bolt connection, from the own quality and examination process, the influence factors of torque coefficient were discussed, and through the comparative trial, the preliminary study to the influence rule of interference factor to the torque coefficient was conducted. The results showed that the main influence factors were the complete condition of thread, oil pollution on nut and washer, corrosion of connection, inspection circumstance, precision of inspection apparatus, detail of inspection process and warranty period of connection.