To study the mediating role of working memory between sleep quality and symptoms in children with attention deficit hyperactivity disorder (ADHD). The cluster random sampling method was used to select 110 ADHD children and 124 normal children as subjects from grade 3-5 students in two primary schools in Kashgar, Xinjiang Uygur Autonomous Region, China. SNAP-IV, Pittsburgh Sleep Quality Index (PSQI), and visual-spatial working memory paradigm were used for investigation and comparison. Compared with the normal group, the ADHD group had a significantly higher total score of PSQI and scores of subjective sleep quality, sleep latency, sleep efficiency, sleep disturbance, and a higher incidence of sleep quality problems (P<0.001). The working memory score in the ADHD group was significantly lower than that in the normal group (P<0.001). In the ADHD group, the working memory score was negatively correlated with the total score of PSQI (rs=-0.271, P<0.001) and the score of symptoms (rs=-0.439, P<0.001), and the total score of PSQI was positively correlated with the score of symptoms (rs=0.540, P<0.001). Working memory had a partial mediating effect in the influence of sleep quality on symptoms in children with ADHD, accounting for 18.10% of the total effect. Sleep quality issues are observed in some children with ADHD, and working memory plays a mediating role between sleep quality and symptoms in ADHD children.