Background: According to the Self-determination Theory, psychological need satisfaction and gaming motives are potentially salient factors of behavioural addictions such as Internet gaming disorder (IGD). This study examined the mediating role of gaming motives on in-game psychological need satisfaction (i.e., Autonomy, Competence, and Relatedness) and IGD tendency. Methods: Chinese adult online gamers (N=383) were recruited and completed an online anonymous questionnaire survey. The questionnaire was composed of Player Experience of Need Satisfaction (for assessing In-game competence, autonomy, and relatedness), Motive for Online Gaming Questionnaire (for assessing General, Escape, Coping, Fantasy, Skill Development, Recreation, Competition, and Social motives), DSM-5 diagnostic criteria for IGD, and demographic items. With demographic items included as controlled variables, the path analysis using Mplus 7.4 was conducted to predict Rasch-scaled IGD tendency score from the DSM-5 criteria. Findings: In our path model, in-game need satisfaction was significantly related to gaming motives. For example, In-game relatedness was positively associated with Social (β=.43) and negatively related to Recreation and Competition (β = −.20 and −.17). All three types of need satisfaction were positively associated with General Motivation (β range= .23-.30). The significant, direct risk factors for IGD included male gender, In-game autonomy, General Motivation, and Escape motive (β range= .17-.26), while Skill Development and Recreation motives (β = −.16 and −.10) were protective factors.