Open Science is becoming a mainstream scientific ideology in the sciences. However, due to inadequate research infrastructures, limited resources, and a lack of local support, amongst various other difficulties, researchers in developing countries are facing significant hurdles in moving Open Science forward. The Chinese Open Science Network (COSN) was initiated to make the voice of Open Science heard by Chinese-speaking early-career researchers (ECRs) and to bridge the Chinese-speaking community with the broader open science communities. COSN has organized in-person workshops, online journal club sessions, talks, and tutorials, and has translated English articles/blogs into Chinese. Now, the COSN official WeChat account has over 32,000 subscribers, and more than 1,000 researchers/students actively participate in discussions on Open Science. In this talk, I will share COSN's experiences and insights in developing such a grassroots network and provide tips for ECRs in developing countries who would like to start their Open Science initiatives.