An optical element including a first substrate, a second substrate, a first optical film, a second optical film, and a spacer is provided. The first optical film is disposed on the first substrate and has a first surface and a plurality of first optical microstructures. The first optical microstructures are disposed on the first surface. The second optical film is disposed on the second substrate and has a second surface and a plurality of second optical microstructures. The second surface is opposite to the first surface. The second optical microstructures are disposed on the second surface. The orthogonal projection of the first optical microstructures on the first substrate does not overlap with the orthogonal projection of the second optical microstructures on the first substrate. The spacer is disposed between the first substrate and the second substrate. A wafer level optical module adopting the optical element is also provided.