The effects of molecular blending on the charge transport properties of organic semiconductors are studied based on ab initio DFT calculation and quantum nuclear tunneling model coupled with kinetic Monte-Carlo simulation. Two model compounds, [(2,3,9,10-tetrachloropentacene-6,13-diyl)bis(ethyne-2,1-diyl)]bis(triisopropylsilane) (4Cl-TIPS-P) and [(1,2,3,4,8,9,10,11-octafluoropentacene-6,13-diyl)bis(ethyne-2,1-diyl)]bis(triisopropylsilane) (8F-TIPS-P), are blended homogeneously with different ratios, and the system is studied at a temperature ranging from 50 to 300 K. Our result shows that, at high temperature, blending leads to a smooth shift in mobility, whereas at a low temperature, one of the components tends to become traps, thus hamper the charge transport at low concentration. It is found that at 50 K, blending 0.995 mol. % of 4Cl-TIPS-P with 0.005 mol. % of 8F-TIPS-P, whose site energy is 48.1 meV lower than that of 4Cl-TIPS-P, would reduce the electron mobility by three orders of magnitude from that of pristine 4Cl-TIPS-P due to the trapping effect. The results are in agreement with the experimental observations.