Abstarct: The aim of this research is Investigation of Water-baxsed Glycol Mud (WBGM) performance on Fahliyan and Gadvan formations of Azadeghan oil field. Before design of WBGM for this formations, baxse fluids were tested on bentonite samples for determination of the best type of salt and representation of glycol performance. Results represented KCl has better performance in reduction of swelling in comparison to NaCl salt. Also glycol baxse fluid test, displayed the reduction of swelling. After baxse fluids tests, WBGM was designed and tested on formation samples of Azadeghan field. Results prove the suggested fluid reduces swelling in WBGM.