The invention discloses equipment for online measurement of the aging degree of nitride fluorescent powder. The equipment comprises a tank body, a cover body is hermetically buckled above the tank body to form a hermetical cavity body between the cover body and the tank body, the hermetical cavity body is filled with a liquid, optical fiber through holes penetrating upper and lower end surfaces are formed on the cover body, branching Y-shaped optical fibers are hermetically connected with upper ends of the optical fiber through holes, one branch of each branching Y-shaped optical fiber is connected with a light source, the other branch is connected with detection equipment, a sample holder used for placing containers loaded with samplers is arranged in the hermetical cavity body formed between the cover body and the tank body, a heating device is arranged below the tank body, a temperature sensor and a pressure sensor are further arranged above the liquid level in the hermetical cavity body, and the heating device, the temperature sensor and the pressure sensor are all electrically connected with a controller. The equipment has the advantages that the structure is simple, the design is reasonable, and the equipment is convenient to use and can online measure the aging degree of nitride fluorescent powder.