The invention relates to powder passivation equipment and a passivation agent adding device thereof. The passivation agent adding device comprises a passivation agent supply tank for storing a passivation agent; a passivation agent outlet and an inert gas inlet are formed in the passivation agent supply tank; a pressure detection element is also arranged on the passivation agent supply tank; a switching valve is arranged on the inert gas inlet or a switching valve is arranged on an inert gas inlet pipe connected to the inert gas inlet. When the passivation agent adding device is in use, the passivation agent supply tank is filled with inert gas, the inert gas provides a certain pressure for the passivation agent supply tank, the passivation agent is pressed into a powder passivation tank provided with a stirring shaft through the pressure to realize the passivation treatment of corresponding powder, and the pressure decides on the flow rate of the passivation agent; the pressure detection element on the passivation agent supply tank is used for detecting the pressure of the passivation agent supply tank; the pressure in the passivation agent supply tank is changed through the on/off of the switching valve, so that the adjustable control of the adding speed of the passivation agent is realized, and different customer demands are met.