Abstract: During COVID-19 pandemic, the exploratory chemistry experiment course adopted an integrated teaching mode of Online-Merge-Offline (OMO). Online teaching was conducted in the form of carrying out chemical experiment safety education in MOOC of Chinese University, carrying out experimental courses online with the help of virtual simulation, and assigning small projects to guide students to carry out exploratory learning. Offline teaching was conducted in the form of home experiments and laboratory experiments, students explore the small projects assigned online through experiments, and finally carried out the network sharing of “small subject”. This teaching mode can not only improve the teaching efficiency of elective experimental courses, but also improve students’ participation, stimulate students' enthusiasm for experiments, and cultivate students’ research awareness and scientific thinking ability.