Hydrogels are the promising classes of polymeric drug delivery systems with the controlled release rates. Among them, injectable thermosensitive hydrogels with transition temperature around the body temperature have been wildly considered. Chitosan is one of the most abundant natural polymers, and its biocompatibility and biodegradability makes it a favorable thermosensitive hydrogel that has been attracted much attention in biomedical field worldwide. In this work, a thermosensitive and injectable hydrogel was prepared using chitosan and beta-glycerophosphate (beta-GP) incorporated with an antibacterial drug (gentamycin). This drug loaded hydrogel is liquid at room temperature, and becomes more solidified gel when heated to the body temperature. Adding beta-GP into chitosan and drug molecules and heating the overall solution makes the whole homogenous liquid into gel through a 3D network formation. The gelation time was found to be a function of temperature and concentration of beta-GP. This thermosensitive chitosan based hydrogel system was characterized using FTIR and visual observation to determine the chemical structure and morphology. The results confirmed that chitosan / (beta-GP) hydrogels could be a promising controlled-release drug delivery system for many deadly diseases.