The dyeing properties of 100% PLA fabric and PLA/PET union fabric were examined with 4 different types of disperse dyes in this study. Disperse dyes were highly absorbed by PLA fiber in the temperature range of $100{sim}110^{circ}C$, K/S values of dyed PLA fabric with azo disperse dyes were much higher than those with anthraquinone dyes. It was found in the simultaneous dyeing of PLA and PET fabrics in the same bath that disperse dyes were mainly exhausted on PLA fiber at early stage of dyeing and migrated to PET fiber at the elevated dyeing temperature. Consequently K/S values of PET became higher as the dyeing temperature increased. Color differences appeared between PLA part and PET part in the union fabric dyed with 4 disperse dyes.