In magnetic drug targeting (MDT), magnetic nanoparticles (MNPs) coated by biocompatible materials and loaded with drug are injected into blood vessels and are specified to the target by the external magnetic field. Magnetic nanoparticles exhibit superparamagnetic properties when their sizes are smaller than the critical size. They show high saturation magnetization and no remanence at room temperature. The advantages of magnetic drug targeting are: (i) the ability to target specific location in the desired area; (ii) the reduction of the quantity of drug needed to attain a particular concentration in the vicinity of the target; and (iii) the reduction in the concentration of the drug at non-target sites minimizing severe side effects. The objective of this study is to computationally model in 2D, by using COMSOL Multiphysics 4.4 for studying parameters including (i) blood velocity; (ii) particle trajectory; and (iii) capture efficiency of magnetic drug targeting. The range of the studied nanoparticle diameters was 10-1000 nm. Blood vessel in this study is artery. According to our simulation, it was found that bigger nanoparticles have higher capture efficiency than smaller nanoparticles. This is due to the higher magnetophoretic force of bigger nanaoparticles.