The invention discloses an along-dielectric-surface discharge test cavity of organic silica gel for high-voltage IGBT device potting. The along-dielectric-surface discharge test cavity comprises an upper electrode beam, an upper end cover, an upper electrode, a cavity and a lower electrode; a tapping through hole is arranged on the upper electrode beam, and the upper electrode is connected with the upper electrode beam through the tapping through hole; the upper electrode beam is fixedly connected with the upper end cover; the upper end cover is fixedly connected with the cavity; the lower electrode is connected with the bottom of the cavity; a lower electrode positioning hole or a cavity sealing rubber ring positioning hole is arranged at the bottom of the cavity; a lower electrode positioning column and a lower electrode sealing rubber ring fixing hole are arranged at the bottom of the lower electrode; the lower electrode positioning hole and the lower electrode positioning column are matched; the cavity sealing rubber ring positioning hole and the lower electrode sealing rubber ring fixing hole are matched; a rubber ring slot is further arranged at the bottom of the lower electrode; and the spacing is formed between the upper electrode and the lower electrode. By adopting the along-dielectric-surface discharge test cavity, the sealing of the along-dielectric-surface discharge test cavity of the organic silica gel can be improved and the insulation material in the cavity can be precisely positioned.