The junction characteristics between ZnO:Ga (GZO) film and p-Si substrate are discussed in the research. For the transparent semiconductor ZnO, the element Ga is chosen to be the dopant source to produce a high quality n-type ZnO thin film. The ZnO:Ga (GZO) film shows a average transmittance is 84.7% (above 400 nm), a bandgap energy of 3.37 eV, a carrier concentration of 7.29×1013 cm−3and a resistivity of 118 Ω-cm. For the GZO/p-Si junction, it shows a junction barrier height of 0.54 eV with an ideality factor of 1.24. The capacitance-voltage measurement shows that it has a uniform reverse bias depletion layer. The Cheung function is also brought to discussion the diode characteristics.