A biaxially oriented multi-layer composite film comprises a PHA-rich core layer and a heat sealant layer and a second outer skin layer. The core layer comprises a PHA resin at an amount of more than 50 wt % of a total weight of the core layer and a modifier X, the modifier X includes PLA, PLA copolymers, PBSA and PCL; the heat sealant layer comprises a PLA resin and a modifier Y, the modifier Y including PBSA and PCL resins is at an amount of about 20 wt % to 95 wt % of the total weight of the heat sealant layer. The composite film has low SIT and improved home compostability.