The invention discloses an environment-friendly high-precision constant-temperature and constant-humidity weighing device. The environment-friendly high-precision constant-temperature and constant-humidity weighing device includes a base, a housing, a constant temperature box and an operation box, the housing is provided with at least two lower cabinet chambers below the operation box; a water supplementing tank is fixed at the top of the housing; the operation box is of a rectangular frame structure with an opening facing a moving door, and the rectangular frame structure is composed of a left constant-temperature plate, a right constant-temperature plate, a rear constant-temperature plate, an upper constant-temperature plate and a lower constant-temperature plate. Three circulating fansare arranged on the rear constant-temperature plate; heating coils are arranged on the left constant temperature plate, the right constant temperature plate, the rear constant temperature plate, the upper constant-temperature plate and the lower constant-temperature plate; a steam inlet is formed in the upper end of the rear constant-temperature plate; a condenser is arranged on the steam inlet, adamping table and a sample frame are fixed to the lower constant-temperature plate, a weighing balance is fixed to the upper end of the damping table, a humidifier is fixed into one lower cabinet chamber, water with large specific heat capacity serves as a heat conduction medium to heat an operation box connecting pipe through five-face type heat exchange, and heat transfer is more uniform.