Bioreactors are crucial for biopharmaceutical engineering, and their properties have an important impact on cell cultivation. Orbitally shaken bioreactors (OSRs) are gradually gaining more and more attention because of their special operational advantages and suitability for disposable cultivation. In this paper, the performance of OSRs is analyzed in comparison to stirred tank bioreactors (STRs). CFD models were established to investigate the difference in fluid dynamics between OSRs and STRs at the same power input levels. The CFD and experiment data showed that mixing and oxygen transfer needed less energy in OSRs than in STRs. Moreover, the shear stress was still at a low level for agitation behaviors in both OSRs and STRs.