Recently, while the ecosystem disturbance caused by microplastics has emerged as a global environment problem, interest in biodegradable polymers to replace traditional non-biodegradable petrochemical polymers is rapidly increasing. Among several biodegradable polymers, poly(butylene succinate) (PBS) has a relatively low thermal processing temperature and high crystallinity, which is expected to be used in various industries. However, because the mechanical properties of PBS tend to be significantly lower than those of other industrial polymers, its actual commercialization is limited. Therefore, in this study, polylactide (PLA),a material with biodegradable and strong mechanical properties, and surface-modified nanocellulose (CNC), a natural material with high stiffness, were mixed with PBS to enhance mechanical properties. First, by mixing a certain amount of PLA in PBS, it was confirmed through a universal testing machine (UTM) that the optimal increase in mechanical properties occurs when the weight ratio of PBS:PLA is 97:3. Through this study, we succeeded in developing a mechanically reinforced material composed of biodegradable materials, and if we attempt to change the surface modification method of CNC and matrix, it was confirmed that it will be easy to develop biodegradable products with different functions depending on the use.