A portable spray paint filling machine, comprising a machine casing. An air cylinder (1) is provided in the machine casing; an air cylinder fixing plate (2) is fixed below the air cylinder (1); a liquid injection apparatus (2) connected to the air cylinder (1) is provided below the air cylinder (1); a liquid injection apparatus fixing plate (3) is provided on the liquid injection apparatus (2); the liquid injection apparatus (2) is mounted on the liquid injection apparatus fixing plate (3); a back plate is further fixed on the liquid injection apparatus fixing plate (3); the air cylinder (1) is further connected to an air pressure meter (100) and a starting switch (102). The portable spray paint filling machine has the characteristics of being convenient to use and reasonable in structural design, etc. In addition, the machine can save a space due to small size, is wide in applicability, reliable in quality, safe in use and convenient to operate, and usually uses ordinary air input. The machine can be moved during working, and can implement on-site filling in any occasion due to strong arbitrariness and flexibility, thereby greatly improving the working efficiency and achieving high economic value and use value.