Simulations of dynamics of tearing modes based on a 4-field reduced magneto hydro dynamics model are performed, laying an emphasis on interaction with microscopic and transport processes. The simulation results show the importance of turbulent fluctuations for the onset of tearing mode. The helical current perturbation associated with a magnetic island is studied. The perturbed bootstrap current has a structure in the magnetic island (including a phase difference), indicating the need to improve assumptions in the theory of neoclassical tearing mode.