An oil mist collector contains a casing unit, a first filtering unit, a second filtering unit, and a ventilation unit. The casing unit includes an inlet, a first air chamber, a second air chamber, an air guiding orifice corresponding to the second air chamber and communicating with an exterior, and a first recycling orifice arranged on a bottom end thereof and communicating with the first air chamber. The first filtering unit is disposed in the first air chamber and corresponds to the inlet. The second filtering unit is fixed above the air guiding orifice and includes an open rear end, a first lip with a noncircular cross section, a second lip, and a first filtration assembly defined between the first lip and the second lip. The ventilation unit includes a motor and a rotary fan rotatably connected with the motor and secured in the second air chamber.