Abstract: L-poly (lactic acid)(PLLA) and D-poly (lactic acid)(PDLA) having reactivity for condensation polymerization were prepared using lactide as monomer, lactic acid and stannous octoate as initiator and catalyst respectively.A series of stereoblock poly (lactic acid) s were synthesized by the melt blend of PLLA and PDLA via Solid State Polycondensation (SSP).The chain structure, molecular weight and thermal properties of products were characterized by NMR, GPC and DSC respectively.The SSP mechanism was discussed when the homocrystal coexists with the stereocrystal in the same system.The results showed that the technological conditions suitable for the molecular weight increase of the SSP products is 30 h reaction time, relative low content of catalyst and 80% mass fraction of PLLA.Relative lower original stereo-crystallinity of the blend of PLLA and PDLA is beneficial to the molecular weight increase of the final products during the subsequent SSP progress.SSP was occured not only between different optical structure chains but also between the same optical structure chains.