Yak caseins are special materials which has attracted more and more attention of researchers due to its increasing. Succinylation is a useful method of improving the functional properties of protein significantly. This study assessed the effects of succinylation on the functional properties of yak and cow caseins, including solubility, emulsifying property, water and oil absorption capacity, foaming property, and digestibility. Six succinylated levels of caseins were prepared by adding different amounts of succinic anhydride to caseins. The succinylated degree of yak and cow caseins was different when similar amounts of succinic anhydride were added. Succinylation improved solubility, emulsifying activity, water and oil absorption capacity, and reduced foam stability and digestibility of yak and cow native caseins. However, succinylation decreased foaming capacity and emulsion stability of cow caseins while increased them of yak caseins. The functional properties of caseins changed irregularly with increasing levels of succinylation. The findings of this study revealed that succinylation had different effects on the functional properties of different sources of caseins. The results will provide the basic data of functional properties of yak native caseins and succinylated yak caseins.