With the dramatic increase of information amount, the technology of cloud service is gradually valued by people. To resolve the problems of mass data storage and scalability above TB or PB level, the operators begin to develop various distributed open source databases at low cost. For example, Google Bigtable, Yahoo, Amazon and Azure cloud platforms are all engaged in the development of NoSQL databases, among which we will mainly focus on Apache HBase in this paper. It will explore its column-oriented data access service and data storage of HDFS file in Apache Hadoop platform. Finally we will discuss about how to access HBase database.