Poly(ethylene adipate) (PEA) and polytetramethylene ether glycol (PTMEG) were used as compatibilizers in the biodegradable polymer blend of poly(l-lactic acid)/poly(butylene succinate-co-l-lactate) (PLLA/PBSL). The compatibilizers of various contents were incorporated into the blend using a Haake internal mixer. The compatibilization between PEA and PTMEG on the blends was measured using thermogravimetric analysis (TGA), flexural test, field emission scanning electron microscopy (FESEM), and Fourier transform infrared (FTIR) spectroscopy. From the TGA results, it was found that the thermal stability of the blend improved with the addition of PEA. The flexural strength showed a dependency on the extent of the secondary forces interaction between PEA and PTMEG with the blends. This observation corresponded well with the FESEM micrographs. Based on the FTIR analysis, the physical interaction between PEA and PLLA/PBSL was due to the presence of secondary forces.