Abstract: Abstract: This paper discussed the dyeing of PLA yarn using seventeen kind of disperse dyes with various structure under different experimental conditions. The results showed that Disperse Rubine R167, Disperse Orange 030, Disperse Blue 284 could be as tricolor dye in PLA dyeing. According to the analysis to these dyeing structures in this paper, it could be found that the PLA yarn would get higher dye uptake though using the monoazo disperse dye with acetate group. After optimizing the dyeing process, the PLA yarn could obtain high quality dyeing effect when the condition were controlled with PH value 4~5, temperature 110℃ for 30~40min. The color fastness to perspiration and washing of dyed yarn could be raised 1~1.5 grade when detergent FB was included into reduction clearing conditions.