The utility model relates to an outdoor isolation switch mechanism box, in particular to an outdoor isolation switch mechanism box with a rainproof function, which comprises a box body, a through holecommunicated with the inside of the box body is arranged at the upper end of the box body, an output shaft in the box body penetrates out of the through hole and is connected with a vertical connecting rod, and a rainproof disc is arranged on the vertical connecting rod. Rainproof protection is carried out on the mechanism box, and the problem that internal elements rust due to rainwater permeation is avoided.