A one way valve assembly including a base, a cover, and a valve member is provided. The base includes a first and a second lower hollows and an inlet communicated with the first lower hollow. The cover includes a first and a second upper hollows, a connecting path, an outlet, and an exhaust nozzle. Positions of the first and the second upper hollows correspond to positions of the first and the second lower hollows. The first upper hollow is communicated with the second upper hollow via the connecting path. The outlet is communicated with the second upper hollow. The valve member is disposed between the base and the cover. The valve member has a first zone, a second zone, and a third zone corresponding to the first and the second upper hollows and the connecting path, and includes a valve nozzle between the second lower hollow and the second upper hollow. The first zone can deform towards the first lower hollow or the first upper hollow. The second zone can deform towards the second lower hollow or the second upper hollow. The third zone can deform towards the connecting path.