In order to further understand glass forming rules of uranium alloy systems, the characteristics of glass formation in U-Rh system were studied in this paper. A series of U-Rh alloys with 65~80 at.% U were designed in the U-rich eutectic zone, and then shaped into ingot samples by vacuum arc melting and ribbon samples by melt-spinning. These samples were surveyed to determine their phase constitutions and thermal behaviors by using X-ray diffraction and thermal analysis means. It is found that upon rapid solidification, U₇₀Rh₃₀ alloy formed partial amorphous phase, having the crystallization temperature of 642 K and the crystallization activation energy of nearly 200 kJ/mol. The coexisting phase was high temperature g-U solid solution, as the first evidence of this kind of phase forming in U-based amorphous alloys through rapid quenching, implying unique non-equilibrium solidification phase transformation of U-Rh alloys. The results indicate that U-Rh is a new amorphous alloy system, however, possessing weak glass forming ability. This is probably relevant to the capability of directly arresting high temperature g-U solid solution during rapid cooling.