We studied the reverse current emission mechanism of the Mo/β-Ga2O3 Schottky barrier diode through the temperature-dependent current-voltage (I-V) characteristics from 298 to 423 K. The variation of reverse current with the electric field indicates that the Schottky emission is the dominant carrier transport mechanism under reverse bias rather than the Frenkel-Poole trap-assisted emission model. Moreover, a breakdown voltage of 300 V was obtained in Fluorinert ambient with an average electric field of 3 MV/cm in Mo/β-Ga2O3 Schottky barrier diode. The effects of the surface states, on the electric field distribution, were also analyzed by TCAD simulation. With the negative surface charge densities increasing, the peak electric field reduces monotonously. Furthermore, the Schottky barrier height inhomogeneity under forward bias was also discussed.