By hosting a college students' laboratory skills contest, we provide an interesting activity for students to cultivate good laboratory practices and thereby improve their laboratory skills. The substance of this contest is the detection of the hardness of water, which involves numerous laboratory skills such as solution preparation, weight by difference mass measurements, glassware calibration, pipetting, quantitative transfer, titration, data processing, and cleaning up the laboratory. Initially, due to limited class time, students are unable to master and practice effectively the skills taught in class. Many students wanted to practice these skills at a time after class, and these skills were subsequently redesigned and organized as an extracurricular activity to involve more students. Skills are assigned to students depending on their year: freshmen act as lab assistants to prepare solutions, such as EDTA-2Na, hydrochloric acid, ammonia, and indicators. This is a simple skill that aims to build confidence in mastering chemical experiments, as such experiments are rarely conducted in high school. Sophomores conducted experiments as contestants. Through the contest, students' laboratory skills are improved and evaluated. The task for senior students is to provide guidance to freshmen and sophomores, identify their mistakes, and demonstrate the correct operations. All of the students collaborated to complete this activity.