Background: The diagnostic guideline of Gaming Disorder was a new category proposed in the draft of ICD-11 by WHO’s Department of Mental Health and Substance Abuse (MSD) in 2018 and its reliability and clinical utility based on Chinese population has not been studied. The purpose of this field study is to clarify the reliability, clinical utility, and culture applicability of diagnostic guidelines of gaming disorder in ICD-11, and its comparability to the diagnostic guideline in DSM-5 in China. Methods: Participants included 21 pair clinical raters which constituted of seven psychiatrists and 200 gaming players aged from 15-18 years old with different risk level of Internet addiction based on the scores of Young’s Internet Addiction Test. Each participant received a semi-structured face-to-face interview by a paired clinical raters at the same time. Then clinical raters made the diagnoses and filled the clinical utility questionnaire independently within 30 minutes after the interview through an electronic platform according to the diagnostic guidelines for gaming disorder in both ICD-11 and DSM-5. In addition, two focus groups were conducted to inform the applicability, feasibility and preference of diagnostic guidelines for gaming disorder in ICD-11 in China. Outcomes: The diagnostic consistency coefficient (kappa value) between the paired clinical raters was 0∙545( p <0∙001), and 0∙622( p <0∙001) for ICD-11 and DSM-5 diagnostic guidelines for gaming disorder respectively. And the diagnostic consistency was 0∙847( p <0∙001) between ICD-11 and DSM-5 diagnostic guidelines for gaming disorder. It indicated 86∙7% of the participants agreed it provide detailed enough implementation characteristics, and showed good overall clinical applicability (86∙0%), specificity (94∙4%), usefulness (84∙1%), as well as acceptable cultural adaptation (74∙8%) for ICD-11 diagnostic guidelines of gaming disorder. ICD-11 was slightly more accepted than DSM-5 in terms of ‘easy to use, accuracy of diagnosis, sufficient detail and specificity’ ( p <0∙05), while the clinical efficiency of ICD-11 was inferior to DSM-5 ( p =0∙035). These results was also confirmed in focus groups, but the participants also suggested that it will be helpful to define refinement of criteria, more detailed strict definition of the scope of diagnosis, and even a connection with relevant laws and regulations. Conclusions: This study indicated the ICD-11 diagnostic guidelines of gaming disorder had acceptable clinical reliability and high consistency with DSM-5 diagnostic guidelines for gaming disorder. Its clinical applicability and cultural adaption are comparable with DSM-5 and it is agreed that the ICD-11 diagnostic guidelines for gaming disorder is a great step committed to reducing the serious consequences caused by excessive gaming behavior through normative diagnosis and timely intervention, especially for adolescents, although further capability buildings and and policy advocacy is needed for better implementation in China. Funding Statement: This work was supported by National Key R&D Program of China (2017YFC1310400), National Nature Science Foundation (81771436), Program of Shanghai Academic Research Leader (17XD1403300), Shanghai Municipal Health and Family Planning Commission (2017ZZ02021, 2018YQ45,20184Y0134), Shanghai Municipal Science and Technology Major Project (2018SHZDZX05), Shanghai Mental Health Center Clinical Research Center (CRC2018YB02). Declaration of Interests: We declare no competing interests. Ethics Approval Statement: The study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of Shanghai Mental Health Centre (Approval number given by the Ethics Committee: 2019-73). All the participants were fully informed of the purpose of the study, the process, signed the informed consent and promised not to disclose the privacy of any participant, and guardians of the participants under 18 year old also need to be fully informed and signed the informed consent.