Recent development in applications of magnetic nanoparticles makes them a good candidate as drug carriers especially for tumor treatment. Therefore it is important to analyze the behavior of magnetic nanoparticles in the blood vessel and tissue. The purpose of the current study is to investigate the magnetic nanoparticles movement and absorption in blood vessel and healthy and cancerous tissue under the influence of non-uniform external magnetic field. An in house finite volume based code is developed and utilized to solve the coupled governing nonlinear differential equations, mass, momentum and concentration under the influence of non-uniform external magnetic field. The 2D cannel is considered as geometry of vessel and blood is assumed to be non-Newtonian. The power law equation is used for blood viscosity. Results show the absorption of magnetic nanoparticles is low in cancerous tissue without of magnetic field, but by applying magnetic field absorption of them multiplied. Also, ratio of magnetic nanoparticles absorption in healthy tissue to cancerous tissue decrease sorely by applying magnetic field. Therefore, treatment is more effective and has fewer side effects by applying magnetic field.