The invention provides a constant temperature and humidity power transformation cabinet which comprises a cabinet body, a temperature regulation module, a humidity regulation module and a control module. The cabinet body is of a sealing structure formed by a first side wall, a second side wall, a third side wall, a door, a top plate and a bottom plate; the first side wall, the second side wall and the third side wall are respectively of a hollow structure; a first multi-way pipe is arranged in the top plate, and a second multi-way pipe is arranged in the bottom plate; cooling liquid is injected into a first side wall inner cavity, a second side wall inner cavity, a third side wall inner cavity, the first multi-way pipe and the second multi-way pipe; the temperature regulation module comprises a circulating pump, a refrigerating plant and a temperature sensor; the humidity regulation module comprises a first air pipe, a second air pipe, a first draught fan, a second draught fan and a first humidity sensor; the control module is respectively connected with the circulating pump, the refrigerating plant, the temperature sensor, the first draught fan, the second draught fan and the first humidity sensor. Thus, the problems that heat dissipation is difficult and damp is prone to accumulation of the power transformation cabinet are solved.