One of the main challenges that hugely effect readers’ performance is cognitive load. It plays a pivotal role to facilitate readers to learn, memorize, and digest a piece of novel information. However, cognitive load can also have insignificant impacts on reading task when the cognitive demands of the reading task when to solve a complex problem. This article proposed a computational model of cognitive load during reading task, based on Cognitive Load theory, to get deep understandings on the dynamics of cognitive load and how the different types of load like intrinsic, extraneous and germane load are affecting the level of cognitive load. A number of simulation experiments were conducted and the results showed that the model is able to produce realistic behaviours under different personalities and conditions. Furthermore, an automated verification was implemented to evaluate the model.