Vendor managed inventory system is vendor centric inventory system in which all inventory decisions are taken by vendor rather than buyer. This study considers non-instantaneous deteriorating items with generalized type time dependent deterioration rate when demand rate is quadratic function of time and shortages are allowed with partial backlogging. The paper aims to compare traditional inventory system and vendor managed inventory system by analyzing total cost function. To validate the model, numerical example and sensitivity analysis are performed. The analysis shows that vendor managed inventory is more beneficial compare with the traditional inventory system.