Plate and cultivation experiments were carried out to investigate the effects of selenomethione (SeMet) (0, 0.5, 1.0、2.5, 5.0, 10.0, 20.0, 40.0 μg g^–1) on the growth of mycelium and fruiting bodies, the SeMet uptake and transformation, and its effects on the nutritional components and mineral elements. A dose response can be observed in the A. auricular mycelium when exposed to SeMet, the IC20, IC50 and IC80 of SeMet to mycelium was 7.6 ± 0.6, 14.5 ± 2.5, and 27.5 ± 7.2 μg g^–1. SeMet supplementation increased the concentrations of organic Se up to 15.1 μg g^–1, 167.3 times higher than the control (40 μg g^–1 treatment). High concentrations of SeMet (≥10 μg g^–1) significantly decreased the biomasses of A. auricula. The 40 μg g^–1 SeMet treatment did not affect the polysaccharide and protein, but significantly decreased the total amino acids and essential amino acids in fruiting bodies. SeMet addition (0.5–40.0 μg g^–1) decreased the concentrations of Fe, Zn, Cu, and Cr in fruiting bodies of A. auricula. The results indicate that SeMet can be used as a Se source for A. auricular, but at appropriate concentrations.