Structure and thermal stability of nano-sized dispersoids in Al-(Zr)-(Pr)-(Cr) alloys have been revealed by conventional and high-resolution transmission electron microscopy. Al-0.16Zr-0.26Pr-0.18Cr alloy (wt.%) illustrates significant precipitation strengthening, thermal stability and inhibit-recrystallization ability by forming a relatively high density of coherent and well-dispersed Pr-containing (Al, Cr)3Zr dispersoids (15 - 20 nm) with L12 structure. The dispersoid is coherent even exposed at 500℃ for 400 h. Pr-containing (Al, Cr)3Zr dispersoid is finer and coarsening-resistant around 500 癈, as compared with L12-structured Al3Zr and Pr-containing Al3Zr dispersoid.