The PLGA (75/25 ) (poly-[lactide-co-glycolide ] ) is a main material of the biopolymer composite to develop cartilage and bone scaffold in this thesis. In cartilage tissue scaffold, improve the acid questions of polyester polymer (PLGA) in the degradation process and mimic host compositions in extracellular matix (ECM). So, after grafting PLGA (50/50) with PEI first, and then mix and make the porous scaffold with PLGA (75/25). Moreover, hyaluronic acid (hyaluronan, HA) was immobilized onto the surface of macroporous biodegradable poly(d,l-lactic acid-coglycolic acid) [PLGA] scaffolds to enhance the attachment, proliferation, and differentiation of chondrocytes for cartilage tissue engineering. In bone tissue scaffold, the same problem for solve PLGA not to be acid problem, and mimic the bone tissue by calcium phosphate salt composition. We blend PLGA (75/25) and hydroxyapatie rich (HAp-rich/β-TCP)、β-tricalcium phosphate rich (β-TCP-rich/HAp) with different ratio to evaluate. The characteristic were evaluated by SEM (scanning electron microscopy), NMR (nuclear magnetic resonance), FTIR (Fourier Transform Infrared spectrometry), GPC (Gel Permeation Chromatogrpahy) and XRD (X-ray diffraction). Soak the experiment in PBS and cell toxicity for in-vitro test. The results show the modification of cartilage scaffold with Hyaluronic acid. Which the pH value is 7.15 after PBS for one month soaks. And scaffold of pure PLGA and PLGA/PEI have 6.5 of the pH value only left. Carrying on cell's toxicity to observe with balb' 3T3 cell-line further, PLGA/PEI/HA proves that does not have cell's toxicity compared to controlled. The other hand, after PBS in-vitro for 44 days in the bone scaffold materials showed the pH value decrease the least (still have 6.85) at PLGA/HAp (2/1) composite, with balb' 3T3 cell-line culture prove that cell's activation has no toxicity. So this cartilage scaffold and bone scaffold developed in this research have potentiality of using very much.