An infrared projection lens assembly includes, in order from the image side to the image source side: a stop, a first lens with positive refractive power, a second lens with refractive power, and a third lens with positive refractive power, wherein a radius of curvature of an image-side surface of the first lens is R1, half of a maximum view angle (field of view) of the infrared projection lens assembly is HFOV, a focal length of the infrared projection lens assembly is f, and following condition is satisfied: −18.2