Abstract: ABA triblock copolymers with polypivalolactone(PPVL) as hard blocks and with polyl, 2-propandiol adipic acid esters(PPA), polybutadienc(PBD) and hydro-genated polybutadiene(HPBD) as soft blocks such as PPVL-PPA-PPVL, PPVL-PBD-PPVLand PPVL-HPBD-PPVL, and ABC triblock copolymer with PPVL and polya-methylstyrene (PaMS) as hard blocks and PBDas soft block, such as PPVL-PBD-PaMS were synthesized. It was discovered that there existed linear relationships of 1/T_m(T_m, melting point of crystalline PPVLin copolymers) against [ssoft block][/PPVL].The effects of lowering Tms and dynamical properties by contents of soft blocks in copalymers are in the order of PPVL-PPA-PPVL> PPVL-HPBD-PPVL>PPVL-PBD-PPVL corresponding to the order compatibilities between soft and hard blocks. But the dynamical properties of PPVL-PBD-PaMS are -lower than that of PPVL-PBD-PPVL and PaMS-PBD-PaMS because it is imcompatible between crystalline PPVL and random PaMS blocks.