Abstract: A probability model based on Bayesian principles is given to measure the semantic association from a concept to its direct-related concept in domain ontology.The model is based on different semantic relationships，and is estimated according to maximum likelihood estimation.Semantic distance is used to estimate semantic relationships in estimating period.Based on the proposed model，a method to measure semantic association of any two concepts in ontology is given.Experiment results of semantic retrieval on open data show that semantic query expansion performs better than classic semantic query expansion.

Key words: domain ontology, semantic relationship, semantic associative degree, semantic distance, probability estimation

摘要： 根据贝叶斯定理提出一种衡量领域本体中概念间语义相关度的概率模型。该模型定义在不同语义关系之上，基于极大似然估计法利用语义距离来对语义关系进行参数估计。并在此基础给出一种计算任意两个概念之间语义相关度的方法。公开数据集上的实验结果表明该方法估计出的概念语义相关度具有相当的有效性，应用在语义查询扩展中可明显提高检索效果。

关键词: 领域本体, 语义关系, 语义相关度, 语义距离, 概率估计