With the larger size and higher parameter of equipment,sealing problems for flange connection have appeared more and more prominent,meanwhile solving these problems timely has also become more and more important.It is an urgent and worthy discussion about how to select gaskets properly for large-diameter flanges.According to the characteristics of large diameter flange connection,and combined with the characteristics of various gaskets,the gasket selecting suggestion for large-diameter flange was put forward.Besides,combined with the engineering practice,application examples were introduced where the connection sealing problems for large-diameter flange have been solved by adopting the latest patent products-double metal self sealing composite gasket.