FeSe film was prepared on GaAs (001) substrate by low pressure metal-organic chemical vapor deposition. The x-ray diffraction measurement indicated that the sample was preferentially oriented with tetragonal structure. The structure relationship between FeSe epilayer and GaAs (001) substrate has been studied. The critical behavior in the temperature-dependent resistivity at ∼290K is close to the Curie temperature, which confirmed that the transformation from ferromagnetism to paramagnetism could be responsible for the critical behavior.