In this paper, to improve the electronic parameters of silicon nanowires, the influence of As and P dopants are investigated. These electronic parameters include transmission spectra, mobility, mean free path and energy band diagram. To study the conduction mechanism and mobility of the Sinanowires, carrier transport along the long nanowires in presence of many defects (including dopant, vacancy, disorderly and surface roughness) has been investigated. In this paper, to simplify the calculations, short Si nanowires with small amount of defects are considered. Therefore, short length silicon nanowires have been doped by As and P and the effects of the dopants have been analyzed. Simulation results demonstrate that, by increasing the energy, transmission spectra increases. It is shown that mobility decreases in carrier concentration more than and for concentration less than this value, mobility is approximately constant.