The present invention relates to a stable oral liquid pharmaceutical composition of celecoxib or its pharmaceutically acceptable salts thereof. The celecoxib present in the compositions as described herein do not show any precipitation when subjected in Fasted State Simulated Gastric Fluid (FaSSGF) at pH 2.0 temperature of 37°C ± 0.5°C and under stirring at a speed of 50 rpm at least for 60 minutes. It also relates to the process of preparing and method of using said composition of celecoxib.