Abstract In this paper, two different detection methods, photoionization and autoionization, are combined to study the spectrum of highly excited states of Eu atom. On the one hand, the bound Eu spectrum with odd-parity in the region of 43927—45010 cm-1 has been measured. The spectral information, such as position and intensity, of 32 transitions can be deduced from the spectra with calibration and the error estimation. The information of excitation process and the selection rules enables us to determine their total angular momenta. Comparison with the related literature show that 12 of the states are newly discovered. On the other hand, we design an effective method to identify different types of highly excited states. The spectra of odd-parity states in the same region are measured by both photoionization and autoionization methods, from which we may separate the Rydberg states from the valence states. of the 32 transitions only 14 can be identified as Rydberg states, and the others are valence states. Furthermore, the effective quantum numbers of the Rydberg states are also discussed in detail with the quantum theory.