Objective:To investigate the clinical features, treatment and follow-up of children with early-onset antinuclear antibody (ANA)-positive juvenile idiopathic arthritis (JIA).Methods:Eighty-six oligoarticular JIA patients with early-onset arthritis (≤6 years old) admitted to the Children′s Hospital Affiliated to Capital Institute of Pediatrics from January 2017 to December 2019 were included in this study. According to ANA titer, these patients were divided into two groups: ANA-positive group (44 cases) and ANA-negative group (42 cases). Clinical data including demographic data, clinical features, laboratory testing results, treatment and follow-up data were statistically analyzed.Results:The ratio of male to female was 7∶37 in the ANA-positive group and 15∶27 in the ANA-negative group and there was significant difference between the two groups ( P=0.035). The proportions of patients with increased C-reactive protein and erythrocyte sedimentation rate were higher in the ANA-positive group than in the ANA-negative group [18.18% (8/44) vs 16.67% (7/42) and 29.55% (13/44) vs 19.05% (8/42), both P>0.05]. The most commonly involved joints in the ANA-positive group were knee (95.45%, 42/44), ankle (20.45%, 9/44) and wrist (18.18%, 8/44), and unilateral asymmetric joint involvement accounted for 81.8% (36/44). In the ANA-negative group, the involved joints were knee (85.71%, 36/42), ankle (14.29%, 6/42), wrist (14.29%, 6/42) and hip (11.90%, 5/42), and 27 out of the 42 cases (64.29%) had unilateral asymmetric joint involvement. There was no significant difference in the above indexes between the two groups (all P>0.05). There were seven cases (15.91%) with uveitis in the ANA-positive group and two cases (4.76%) in the ANA-negative group, and the difference between the two groups was significant ( P=0.045). Before treatment, the ANA-positive group had a significantly higher disease activity score (JADAS27) than the ANA-negative group (14.43±2.87 vs 12.09±3.32, P=0.002). After treatment, the JADAS27 score in both groups decreased (both P<0.05). After six months of treatment, the two groups had similar clinical remission rates [70.45% (31/44) vs 76.19% (32/42), P>0.05]. Conclusions:Early-onset ANA-positive JIA was more common in female children, and asymmetric knee joint involvement was the most common clinical manifestation. The incidence of ophthalmic complications was high, and ophthalmological examination should be performed more frequently during follow-up. The prognosis of early-onset ANA-positive JIA was good with early treatment. Positive ANA was not a risk factor for poor prognosis.