Based on the GBEE-CRAS 2020 and the ESG Reporting Guide，ESG reports released by mainland companies listed on the Stock Exchange of Hong Kong Ltd. （SEHK） in 2020 are assessed in this research. It aims to help the mainland companies listed in the SEHK effectively improve their ESG management and information disclosure，further meet the requirements and expectations of regulators，investors and other stakeholders，and facilitate their sustainable development. It is found that the overall quality of target reports is higher than the overall ESG reporting quality in China，and the reports have the following characteristics：for the first time，the overall quality of the reports scored 60；the report quality has upgraded as a whole，and is in the “catch-up” stage on average；on the whole，the information disclosure about employees，investors，customers，environment，community，government，suppliers and other stakeholders is highlighted，while the information disclosure about relevant parties such as media，peers，social organizations and financial institutions is relatively insufficient；performance comparability is better than the overall level of companies in China；the vertical and cross-industry comparison is significantly improved，with more than 70 percent has cross-year performance comparison；in the field of environment issues，the disclosure of issues such as emissions and resource utilization is relatively high，while the disclosure of ecosystem protection and special fund is generally insufficient；in the social field，the disclosure of issues such as product/service quality，social security，occupational health and safety is relatively high，while the disclosure of product/service information，trade union，supplier management，community employment training and other issues is not paid enough attention to；the internationalization of reports has been enhanced and more attention has been paid to communication with global stakeholders. According to the evaluation results and the actual situation，the following suggestions are proposed accordingly：the full lifecycle management of ESG disclosure should be strengthened to improve the report quality；the collection of key performance data should be standardized to enhance the comparability of reporting performance；the information disclosure of ecosystem，biodiversity，climate change，carbon capture/carbon compensation，and environmental funds should be improved to show the initiative and foresight of companies to deal with environmental risks；health and safety，labor rights，product responsibility，customer information and privacy protection，supply chain management and other information disclosure should be strengthened to enhance the responsible competitiveness；the information disclosure that the board of directors or the top management engage in，guide or supervise the management of CSR should be strengthened to improve the governance；overseas communication should be targeted to enhance the global influence of companies.