In　this　paper,　molecular　dynamics　simulations　were　performed　to　reveal　the　dependency　of　glass　transition　temperature　and　shape-memory　effect　of　amorphous　poly　(L-lactide)　(PLLA)　on　its　molecular　weight.　It　was　demonstrated　that　increasing　molecular　weight　of　PLLA　leads　to　increase　of　glass　transition　temperature,　which　is　attributed　to　the　increase　of　fixed　phase.　The　shape　memory　effect　of　PLLA　was　presented　through　simulations　of　deformation　and　recovery,　by　which　the　shape　recovery　mechanism　of　the　amorphous　polymer　was　explained.　The　shape　fixity　ratios　of　PLLA　with　different　molecule　weights　remain　about　83%-90%.　The　characteristics　of　shape　recovery　stage　of　PLLA　under　two　different　heating　processes　were　examined:　under　gradual　heating,　the　recovery　rate　was　observed　to　decrease　and　eventually　became　stable　as　the　molecular　weight　was　increased;　under　constant　temperature　heating,　the　recovery　rate　was　observed　to　first　exhibit　an　increase　and　subsequently　a　decrease　as　the　molecular　weight　was　increased.　Additionally,　after　the　second　thermal　cycle,　the　fixed　rate　is　found　to　change　slightly,　while　the　recovery　rate　is　increased.　This　research　provides　guidance　for　obtaining　ideal　shape　memory　materials.