The production of <sup>177</sup>Lu, a vital medical isotope utilized in imaging-guided radiotherapy, depends on the irradiation of high-abundance <sup>176</sup>Lu or <sup>176</sup>Yb. With an increasing demand for medical isotopes, enhancing the supply capacity for <sup>177</sup>Lu is crucial. The multi-step multi-color photoionization method is an effective way to access isotopes, while the information of odd-parity autoionization levels is essential. Laser resonance ionization spectroscopy is one of the few spectroscopic experimental methods that can study autoionization levels. An experiment system is developed for the frontier spectroscopic research, consisting of custom-made tunable lasers and a high-resolution time-of-flight mass spectrometer. The delayed photoionization method is used to measure the lifetime of the excited state 35274.5 cm<sup>-1</sup> for the first time as 31.6 ±1.7 ns. A three-step three-color photoionization process is employed to explore the autoionization levels, with a 30 ns delay between λ<sub>2</sub>-λ<sub>1</sub> and λ<sub>3</sub>-λ<sub>2</sub>respectively to avoid any unexpected transitions. Forty-seven odd-parity autoionization levels are accessed, 33 of them are found for the first time, and the λ<sub>2</sub>, λ<sub>1</sub> are blocked respectively to exclude possible interference peaks like the λ<sub>1</sub>+λ<sub>3</sub>+λ<sub>3</sub>transition. Several autoionization levels show asymmetrical peak shapes, and the Fano fitting is carried out for all the levels to determine the widths and relative transition strengths of the autoionizing transitions. This provides critical data for the high-efficient photoionization of lutetium atoms in the visible range. The angular momentum of 21 odd-parity autoionization levels in the energy region 50650 ~ 51650 cm<sup>-1</sup> is identified for the first time, which provides a reference for determining the forbidden situation of electric dipole transitions from other excited states and ascertaining the electronic configuration.
