This paper presents a QTI compliant assessment system developed on handheld devices such as Smartphone that consists of several major components to achieve a robust and sufficient mobile testing environment. The proposed system also takes account of the problems, assessment suspending and time-consuming process due to impermanent wireless connection and relatively weak computing power respectively. Therefore, through the implemented assessment download function and user’s behaviors tracking mechanism, the user can accomplish the required exams without considering the restriction of network status. The entire system includes the supporting of an Assessment Management System (AMS), and an exam reader on client platform both are based on web service technology.