Auditing is a continuous process that involves collection of audit evidences. Continuous auditing (CA) is an active research domain of computer assisted auditing in an informationization environment. Online auditing as used in China is one mode of continuous auditing. Electronic audit evidence (EAE) is a main form of audit evidence in an informationization environment. Quick and accurate electronic audit evidence in an online auditing environment has become an important decision problem for auditors in today's economy. Studies on this issue are very limited. This paper provides alternative quantitative tools to assist audit evidence gathering in online auditing environments. First, the concept of online auditing is analyzed; then, according to the characteristics of online auditing, an audit evidence gathering model is proposed. In addition, audit risk assessment methods of the audit evidence gathering model are proposed. Finally, we analyzed the benefits and drawbacks of this audit evidence gathering model.