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The usage of medium‐voltage switchgear is more and more common in high altitude areas. Few relative standards about the selection of switchgear air gap in low air pressure conditions are currently available for referring. In this study, four different types of switchgear air gaps, as well as a typical rod‐plane gap, are taken as the samples, and their positive and negative lightning strike discharge characteristics under low air pressure are tested in the artificial climate chamber. The effects of the electrode structure, polarity, air pressure, humidity, and gap distance on the discharge performances are analysed as well. Research results indicate that the four switchgear air gaps and typical rod‐plane gap differs greatly in lightning impulse discharge performances and polarity effects. In low air pressure conditions, the lightning impulse breakdown voltage of either positive or negative polarity can be corrected by U50 = U50,0 × (P/P0)n. The discharge voltage under positive lightning impulse is more easily affected by air pressure than that under negative lightning impulse. Atmosphere humidity will cause dispersiveness of air‐gap lightning impulse discharge voltage, which performs to be non‐linear with a gap distance lower under 400 mm. Research results are referable for the design, selection and installation of medium‐voltage switchgear in high altitude areas. [ABSTRACT FROM AUTHOR]