Digital learning time has come, and the network teaching platform is one of them. Without the real physical situation of contact, the user interface of platform is responsible for message delivery and reception, the impact of the extent of the smooth interaction of users and websites, learning outcomes, teaching quality, and willingness to continue through this platform of teaching and learning. "E-Learning Service Center at Ministry of Education" implements teacher in-service training, and it passes the concept of the 12-year national education policy to the country’s elementary school and high school teachers effectively and quickly. "E-Learning Service Center" has operated since March 2010 and had accumulated 17.9 million passengers in four years. The platform usage increases every year. This study uses "heuristic evaluation" and invites five experts with digital learning and multimedia practical experiences to evaluate the platform. Then, "usability testing" complemented by eye-tracking and software recording are proceeded by 13 testing-users. At last, "interviews and satisfaction surveys" are proceeded by the above 13 testing-users. This study makes a collection of the above three cross-comparison research data to evaluate and explore usability problem of the platform, and at the same time get conclusions and recommendations of this study. Research finds that 13 testing-users evaluate satisfaction of the platform to be ordinary (OK) in description, the average SUS score of 53 points (the standard deviation of 18 points).The website design is generally in line with " consistency and standards," " match between system and real world," " recognition rather than recall ,"" aesthetic and minimalist design," for the requirements of this 4; but in the " visibility of system status," there is room for improvement; moreover, experts think it’s lack of "flexibility and efficiency of use "and" user control and freedom " as well as testing-users think it’s lack of " error prevention, recovery, and guidelines " in design. In addition, the study also compiles 10 usability issues of this website and proposes 10 recommendations for its future design.