Adjustments in online learning systems during the COVID-19 pandemic have led to an increase in mental workload and fatigue levels among students. This study aims to determine the influence of independent factors and the relationship between mental workload and fatigue levels among Industrial Engineering students during online learning. The research methods used were NASA-TLX and SOFI. The results show a significant influence of marital status on the level of mental workload with a p-value of 0.016, while there is no significant influence of student status and gender with p-values of 0.435 and 0.210. However, there is a significant influence of student status and gender on fatigue level with p-values of 0.008 and 0.000, while marital status has a significant influence with a p-value of 0.326. The correlation test results show that in the NASA-TLX method, 6 pairs of elements have a significant relationship with a p-value of 0.000, while the remaining 8 pairs of elements do not have a significant relationship with p > 0.05. Furthermore, the SOFI method shows all elements have a significant relationship with a p-value of 0.000. The findings of this study can serve as evaluation for institutions to create effective and successful online learning.