In education, computer learning systems make wide use of pedagogical agents to simulate a tutor and/or mimic tutoring interaction, as well as offering just-in-time and adaptive feedback. Although the theoretical aspect of the pedagogical agents has been well-documented in the literature, relatively fewer efforts have been made on how a pedagogical agent should be implemented in a real multimedia computerized simulation learning environment. In this paper, we propose a pedagogical agent architecture and implement it in the multimedia medical simulation web-based learning system call HINTS to further facilitate students' learning and thereby make the HINTS a more effective educational tool. A preliminary students' performance evaluation result is reported. Some experiments have been conducted and the results show that the pedagogical agent indeed help the students in their learning process.