Abstract Research purposes:It is an international development trend to apply the reliability theory to revise the" Engineering Structure Code" ． This paper sums up the thinking of the theory by means of explaining the profound in simple terms，gives the examples to explain the essence of reliability theory，and expounds the significance of revising the " Code for Engineering Structure of Railway Subgrade" ．
Research conclusions:The purpose of revising the " Code for Engineering Structure of Railway Subgrade" is to quantify the reliability of engineering structures．The compiling process of the code with the reliability theory can be summarized as follows: establishment of the limit state equation － giving the statistical characteristics of random variables parameters －calculation of the current standard implicit reliability index － determination of the target reliability index － putting forward the subitem coefficient － establishment of the limit state design expression．
Japanese Railway Comprehensive Technique Research Institute ． Basic Structure Anti Soil Pressure Structure ［M］．Dongjing: MARUZEN Publishing Corporation， 2000．
［7］ 罗一农．重力式挡土墙可靠度设计方法研究［J］．铁道工程学报，2007(8) :27－29．
Luo Yinong． Research on the Reliability Design of Gravity Retaining Wall［J］．Journal of Railway Engineering Society，2007(8) : 27－29．
2012, Vol. 29 
