Pupil size is an important parameter in eye movement research. In the field of cognitiveresearch, pupil size is considered sensitive indicator reflecting cognitive resource allocation and cognitiveload. Given that there are few studies in China that use pupil size as a measure of cognitive load, andthere are even fewer papers reporting on how to preprocess pupil data collected, such as removing,interpolating, filtering, etc., the preprocessing of pupil data lacks reference. This thesis aims to use pupilsize as an indicator of cognitive load during emotional regulation, and to introduce the export andpreprocessing of pupil data collected through the Eyelink2000 eye tracking system. It is hoped that thispaper can provide reference for other researchers.