Abstract: In this paper,design methods for the gas pipeline structure of composites are introduced 6y combining the reliability theory and grey system theory with optimization ,and taking account of influences of white,grey and random factors on the oil or gas pipeline design.A relation between soil temperature and the central depth of a buried pipe is deduced from a grey mathematical model GM(11).A method for selection of the best from transfergas formulas is also introduced in terms of the grey relative ratio.