A mixed flow fan includes a bottom base, an outer cover disposed on the bottom base, a motor disposed on the base, and a hub located between the outer case and the motor. The hub includes a first outer surface and a second outer surface connected to the first outer surface and inclined relative to the first outer surface. The slope of the first outer surface relative to the central axis is greater than the slope of the second outer surface relative to the central axis. The base includes a side surface adjacent to the second outer surface. The slope of the side surface relative to the central axis is equal to the slope of the second outer surface relative to the central axis.