<p>Adolescents in China face intensifying mental health challenges as extraordinary academic pressures rooted in cultural expectations for high achievement. While government-led initiatives provide multilevel formal support structures, critical gaps remain in understanding adolescents’ perceptions of both formal and informal social support adequacy across different phases of mental health problems. This study applied qualitative thematic analysis to semi-structured interview data collected in Anhui Province. Participants included 17 adolescents aged 10–19 years and one 25-year-old whose mental health concerns originated in adolescence (age 15), with 15 family members jointly interviewed alongside them. Four themes characterized participants’ narratives: the early manifestation phase, marked by multilevel barriers to timely mental health intervention, including insufficient parental response, a lack of systematic school-based prevention and stigma among adolescents; the problem escalation phase, characterized by insufficient policy implementation and a demand-execution gap, reflected in barriers to formal support access, insurance issues and disruptions in peer support; the treatment-recovery phase, multi-dimensional support gaps involving medicalization path dependence, limited inter-institutional coordination and inadequate follow-up support for families; and participants’ visions for ideal collaborative support systems. The findings underscore the critical need to strengthen formal support systems for adolescents, which not only shape the identification of mental health needs and resource access but also play a crucial role in fostering adolescents’ psychological development through informal networks such as families and peers.</p>