Although offline courses and face-to-face teaching are still the mainstream the education industry currently, the influence of the Internet has gradually penetrated the education industry since the popularity in 2014. Although online course has been taking over, it still failed to shake the dominance of offline course even in late 2018. However, as the pandemic has trapped most people in their living space since 2020, the Internet now becomes the only connection between people and the world. And it has undoubtedly become a huge opportunity for the online course industry. In the post-epidemic era, the proportion of online courses will gradually decrease, but it is believed that the "online + offline", or so called "online merged offline" (OMO), education model is the general trend. The increasingly popular 5G technologies, VR, AR, and artificial intelligence technologies are likely to enhance online education experience. This article systematically analyzes the development of online and offline courses in educational institutions through PEST mode under the circumstance of COVID-19. This article may also include practical value based on many investigations.