abstract according to the defect of the conventional bayes " method in the geomechanical engineering back analysis, expanding bayes " method was established in this paper . with the applications of the probability theory and the mathematical statistics principle, the geomechanical engineering random back analysis objects function was founded based on the aic criterion of the decision information theory and the maximum entropy criterion, a the matching question between the observed information and the previous information of the conventional bayes " method were proposed . in addition, the least square method, maximum likelihood method and conventional bayes " method were unified in form 本文针对岩土工程反分析中使用的传统贝叶斯法中存在的缺陷,提出了扩展贝叶斯法,从概率论和数理统计的原理出发,建立了基于决策信息论中aic准则和最大熵准则的岩土工程随机反演的准则函数,解决了传统贝叶斯法的观测信息与先验信息的匹配问题,并从形式上完成了目前常用的最小二乘法、最大似然法及传统贝叶斯法准则函数的统一,并可由观测数据的质量和数量进行预测模型的辨识。