We present a photodiodes with a p-ZnO/oxide/n-Si structure in a magnetic field. The N-In codoped p-type ZnO films were deposited by ultrasonic spray pyrolysis on a (111)-oriented silicon substrate with an ultrathin oxide layer. When the p-ZnO/oxide/n-Si structure photodiode was placed in a strong magnetic field, the total current under illumination was enhanced about one order. This may results mainly by the magnetic field-induced photocurrent. An absorption tail of the responcivity shift from 371 to 370 nm, and a blue shift about 9.03 meV was observed. This shift is attributed to the Landau splitting.