In the offset process, ink penetration performance has extremely important influence on the quality of printed products. Ink penetration behavior and ink transfer volume on the offset paper surface were researched with the aid of IGT printability tester (AIC2-5) in the conditions of temperature 20±3°C and humidity of 60 ± 5%. Effect of different printing pressure and printing speed on the ink penetration depth was discussed, and at the same time, the depth was measured by GX71 Inverted Metallurgical Microscope. The results showed that, with the increasing of printing pressure, the changes of ink penetration depth and the ink transfer volume on offset paper surface were increased firstly and then decreased. When printing pressure was 400N, the ink penetration depth reached the maximum 71.67μm and the ink transfer volume reached the maximum too. With the enhancing of printing speed, ink penetration depth and ink transfer volume would be decreased gradually. The study also found that ink penetration behavior had certain influence on the ink color forming properties. For the offset paper used in this experiment, when ink penetration depth was 60.0μm~63.0μm, the print had high ink color intensity and color efficiency. When the ink penetration depth was too deep, ink color intensity and color efficiency was significantly reduced, while the color hue error would be increased, the print ink color turned shallow.