With the droplet observation instrument and industrial microscopy, the states and data of the droplets before and after they impacted the paper were obtained. The spreading of inkjet recording dots on paper surface was analyzed based on luminance data. The reflection coefficients corresponding to the inner and outer edges of the inkjet recording dots were defined and the feasibility was verified. The factors influencing the radius, shape, and blurriness of recording dots were discussed and the spread-ratio of droplet on different paper was calculated.