Orbitronic devices have aroused considerable interest due to their unique advantage of being independent of strong spin-orbit coupling. Light metal chromium (Cr) with high orbital Hall conductivity has significant potential for application in orbit-spintronic devices. In this study, we present experimental verification of the inverse orbital Hall effect (IOHE) in Cr thin films and systematically investigate the underlying physical mechanisms of orbital-to-charge current conversion. The Cr/Ni and Pt/Ni heterostructures are fabricated on Al₂O₃ substrates via magnetron sputtering. Terahertz time-domain spectroscopy is employed to measure the terahertz emission signal. The Cr/Ni heterostructure exhibits the same positive terahertz polarity as the ISHE-dominant Pt/Ni heterostructure, despite the Cr layer owing negative spin Hall angle, which confirms the IOHE of Cr/Ni heterostructure. In the Cr/Ni heterostructures, femtosecond laser excitation generates spin current in the ferromagnetic Ni layer, which is converted into orbital current via its spin-orbit coupling. This orbital current propagates into the Cr layer where it is transformed into charge current through the IOHE. Furthermore, the increase of the Cr thickness (2–40 nm) weakens the terahertz emission of Cr/Ni heterostructures due to enhanced optical absorption of Cr layers reducing spin current generation in Ni layers. However, the optimization of Ni thickness (3–10 nm) significantly enhances the terahertz emission by improving the spin-to-orbital current conversion efficiency. This work provides experimental evidence for IOHE in Cr films and demonstrates the crucial role of ferromagnetic layer engineering in spin-to-orbital current conversion efficiency, providing innovative perspectives for designing and optimizing the performance of orbitronic devices.