In this paper, (001)-oriented hexagonal YMnO3 (h-YMO) thin films with various nominal strain states were deposited on MgO(100), MgO(111), and YSZ(111) substrates by pulsed laser deposition. The in-plane orientation alignment and substrate-induced epitaxial strain between the h-YMO films and substrates are examined by X-ray diffraction (XRD) θ-2θ, Φ, and ω scans. The effects of epitaxial strain on the on-site Mn d-d transition energy Edd (T), and the Néel temperature (TN) in these thin films are investigated by wavelength-tunable ultrafast pump-probe techniques. We find that the changes of Edd (T) and TN depend on the type and magnitude of the epitaxial strain. The possible mechanisms for the observed strain effect on the electronic structure and associated magnetism are discussed.