To confirm the applicability of polarization spectroscopy to complex Sm atoms, we employed two-color two-step resonance excitation and photoionization detection techniques to study the spectra of even-parity highly excited states of an Sm atom. First, through two-step excitation, an Sm atom in the ground state 4f⁶6s²⁷F₀ was excited to the even-parity excited states (angular momentum quantum numbers, J=0?2), and photoionization was used for detection. The spectra were compared and analyzed under different polarization combinations, and the total angular momentum quantum numbers J of the three even-parity highly excited states were determined using the polarization selection rule. Finally, by changing the angle of the vibration directions of the two linear polarized lights, we established the relationship between the photoionization signal and the angle, which verifies the applicability of polarization spectroscopy to Sm atoms.