The invention discloses a technological parameter determining method of metal material 3D printing. The method comprises the steps that range values of the powder layer thickness, laser power and scanning speed parameters are determined; multiple point values are arranged within all parameter ranges in an arithmetic value progression mode; all the point values are in one-to-one correspondence to form multiple I type parameter groups, and metal sample blocks are printed for all the I type parameter groups; the obtained sample blocks are subjected to a hardness test, a I type parameter group value with the highest hardness is selected, upper and lower point values of laser power point values and scanning speed point values in the I type parameter group are determined, and the obtained point values are in one-to-one correspondence to form nine II type parameter groups; tensile test bars are printed for all the II type parameter groups; the obtained tensile test bars are subjected to a tensile test, a II type parameter group value with the best mechanical property is obtained, and then the technical parameter suitable for metal material 3D printing is obtained. Accordingly, by means of a regular parameter combination mode, the parameter range is narrowed through the hardness test, the most suitable parameter is obtained through the tensile test, and the method is simple, reliable, economical and practical.