A study has been conducted to investigate the variation of water quality parameters during January to June of 2014 in Karnafully River of Chittagong, Bangladesh. Water samples were collected from January to June 2014 of each month in 5^th day. Samples of water from three points of Karnafully Rive were collected and brought in laboratory for analysis and analyzed by using different standard prescribed methods. Total eight water quality parameters were measured like as pH, EC, TDS, Total Hardness, Fe, Cl^-, As and Turbidity. All the water quality parameters were attenuated from January (winter) to June (summer) except pH. Another important fact was most of the parameter’s values exceeded the permissible limit recommended by WHO. It is a concerning event for ecology and environment of this catchment area. Our findings will convey a sound message for the government body and policy maker to set up rules and regulation in order to keep ecological balance as well as save our environment and this research will be helpful for public awareness. An immediate attention from the concerning body is mandatory in order to protect the aquatic environment of Karnafully River as well as food chain contamination.