In Shenzhen, despite recent primary and mental healthcare reform, Primary healthcare doctors (PHC) have limited access to diagnostic tools and a significant mental health treatment gap presides. The World Health Organization's (WHO) mental health gap intervention guide (mhGAP-IG.v2) offers a non-specialist and evidence-based guide for the assessment of depression however requires adaptation to the context of use. Bilingual (Mandarin and English) qualitative research was undertaken with 30 PHC leaders from Shenzhen to compare their assessment approach for depression against the mhGAP-IG.v2 in order to identify context-specific modifications for a local guide. Local assessment differentiators included: a need for culturally sensitive translation of depression symptoms; a preference for a broad, non-hierarchical symptom presentation (including somatic, behavioural and anxiety items); national prioritisation of suicide patients; the integration of family into the cycle of care; limited primary care awareness of a depressive episode in Bipolar Disorder; and China's specialist-led diagnostic approach. Contextual modification of mhGAP-IG.v2 is recommended to take account of China's unique cultural and primary health system response to depression. Ongoing mental health training is required to develop professional confidence in the recognition of mental disorders.