Massive open online courses (MOOCs) have attracted increasing attention. Instructors, as an important component of MOOC online collaboration, have not received sufficient attention. Therefore, this paper constructs a hierarchical linear model (HLM) with time variables to study how the instructor group diversity of Coursera specialization affects group performance and how the instructor group diversity of the specialization changes with time. This paper chooses instructor groups of all Coursera specializations from May to October 2018 as the empirical research object, obtains 397 specialization courses, and calculates and analyzes the research object. The results show the following. (1) The duration difference in the continuous opening course by instructor group has a significantly negative impact on the review volume and rating of the specialization, but the negative impact gradually decreases up to a point. Beyond that point, the review volume and rating increase with the increase in duration difference in the continuous opening courses by instructor group. (2) The difference in the teaching field by instructor group has a significantly positive impact on the specialization review volume, but the positive impact gradually decreases up to a point. Beyond that point, the specialization review volume decreases with the increase in the difference of the instructor group teaching field. Unexpectedly, the difference in the instructor teaching field has no significant impact on the specialization rating. (3) In a specialization, the duration difference in the continuous opening course by instructor group decreases significantly over time, as does the difference in the teaching field. Therefore, some suggestions are proposed for the future construction of Coursera specialization.