Nickel (Ni) doped tin oxide (Sn1-xNixO2 x=0.00, 0.02, 0.04, 0.06, 0.10, 0.20) thin films were deposited on glass substrates by a sol-gel method using an ethanol solution containing tin and nickel chloride. The structural and optical properties of Ni-doped SnO2 transparent semiconducting thin films were investigated. X-ray diffraction patterns showed that all samples have tetragonal phases. The morphology of the films showed that the films have good surface and are very dense. The grain size was calculated between 4.4 and 5.3nm by a transmission electron microscope. The electrical measurement showed that the resistivity increases as the Ni concentration increases. The optical properties of the films measured by UV-Vis showed that the films have transparency between 90% and 98%. The extinction coefficient is very small, and the refractive index is saturated at a wavelength >400 nm. The VSM results showed that all the samples are ferromagnetic, except for the lowest Ni dopant. Moreover, the original ferromagnetism can be explained by the bound magneton polaron (BMP) mechanism.