Hydrodynamic calculations of the chaotic behaviors in n+nn+In0.53Ga0.47As devices biased in terahertz (THz) elec-tric field have been carried out. Their different transport characteristics have been carefully investigated by tuning the n-region parameters and the applied ac radiation. The oscillatory mode is found to transit between synchronization and chaos, as verified by the first retu map. The transitions result from the mixture of the dc induced oscillation and the one driven by the ac radiation. Our findings will give further and thorough understanding of electron transport in In0.53Ga0.47As terahertz oscillator, which is a promising solid-state THz source.