The invention discloses a preheating 
powder spreading device for 
selective laser melting metal 3D printing. The preheating 
powder spreading device comprises a 
powder supply tank body, a heat conduction cylinder, a powder spreading tank body, a powder feeding roller body, powder spreading filter screens, a powder spreading 
brush and a forming platform; and powder recycling boxes and a forming working cylinder are arranged at the bottom of the forming platform, a powder spreading mechanism and a powder supply preheating mechanism are installed above the forming platform, the powder spreading filter screens are arranged in a ">" shape, and a plurality of powder spreading through holes are formed in the powder spreading filter screens. According to the preheating powder spreading device, the device only needs to drive the powder spreading 
brush to move left and right to spread the powder, so that the 
energy consumption is saved; the plurality of powder spreading through holes are formed inthe powder spreading filter screens, 
metal powder can be dispersed more uniformly in the process of sliding down of the 
metal powder, and the paving efficiency is higher; large-particle metal particles can directly fall into the powder recycling boxes along 
slag falling grooves in the two sides, and the 3D printing product quality problem due to 
doping of the large-particle metal particles is avoided; and the 
metal powder is preheated in advance, the time for heating and melting the paved 
metal powder is saved, and the 3D printing efficiency is improved.