The Directory of Open Access Journals is a compilation of reputable open access journals. It currently has 16 Chinese journals.
SciencePaper Online is an open access preprint server that covers 43 different STEM fields. Preprints are traditionally defined as manuscripts that have been accepted for publication but haven't been published yet. But some of the preprints in this server haven't been accepted for publication.
Below is a list of various institutional and governmental repositories that are open access:
Hong Kong University Scholars Hub
Hong Kong University Theses Online
Hong Kong University of Science and Technology Institutional Repository
Hong Kong City University Institutional Repository
Hong Kong City University Theses Online
Hong Kong Polytechnic University Institutional Repository
University of Macau Institutional Repository
Shanghai Jiao Tong University Institutional Respository
Xiamen University Institutional Repository
Knowledge Repository of the National Science Library (part of the Chinese Academy of Sciences)
Sharing Enviornmental & Ecological Knowledge Space 寒区旱区科学数据中心
As with all other countries, China has recently seen a rise in 'predatory' open access journals. These publications sole purpose is to generate revenue from author fees, rather than promote scholarship. You can find much more information about predatory open access journals on the Publishing in the Sciences research guide (on the Choosing a Journal tab) and the Open Access research guide (on the Finding a Reputable Journal tab).
Here are a few warning signs that indicate a journal is predatory: