In a GSM system, where coverage areas are divided into cells in planning phase, the division method and its parameters have a great importance. This study explains GSM system and cell planning process, and gives information about the features of fuzzy logic algorithm. Fuzzy logic solves problems better than other control algorithms in which initial parameters are needed to be assigned, by the designer, which have variables that aren't defined well and change with time and where system expert's knowledge and experience in design process have great importance. Cell planning has same important problems that aren't defined well, change with time. These important problems of cell planning are the cell radius, base station number and power, TRU (transceiver unit) number, N (number of cells per Cluster), cost, CIR (channel interference ratio), Ds (distance between two cells which use same frequency at the same time) are found for urban, Suburban zinc rural areas by using omni or three sector antennas. GSM cell planning is simulated by Using fuzzy logic algorithm, a computer program is written to determine what kind Of configuration changes have to be made so as to minimize the number of base station, and hence the total system cost, and also to maintain the requirements of the maximum traffic demand. In addition, input and Output data can be defined through the interface which is created in C++ Builder programming language.