The need of determining the degree of semantic similarity/relatedness between two concepts within ontology is becoming an increasingly important task in the field of Information Retrieval. Semantic similarity is only a special case of semantic relatedness. Although a great attention has been paid to design semantic similarity methods based on ontology, there has been little discussion about the methods of semantic relatedness methods. In this paper, based on distance-based calculation model to calculate concepts' similarity within ontology, we introduced an improved method for measuring semantic relatedness. In addition, our approach considers some important properties such as concepts' depth, density, relation distance to measure semantic similarity/relatedness. The experimental studies are provided to illustrate that our approach is reasonable.