To improve the crystallization properties of poly(lactic acid) (PLA), PLA/TMC blends were prepared by melt blending method using sebacic acid diphenyl dihydrazide (TMC) as nucleating agent, and the effects of the content of nucleating agent TMC on the crystallization properties, thermal properties and mechanical properties of PLA were investigated. The results showed that the nucleating agent TMC had a good heterogeneous nucleation effect on PLA, and pure PLA had no crystallization peaks during the cooling process at 10℃/min, while PLA had obvious crystallization peaks after the addition of nucleating agent TMC, and the cold crystallization temperature of PLA decreased from 117.03℃ to 110.60℃ with the increase of TMC content. In addition, the addition of nucleating agent increased the spherical crystal density and decreased the size of PLA, while the elongation at break of PLA increased by 26.4% with the addition of TMC at a mass fraction of 0.8%.