In recent years, liver diseases have increased to a great extent in a way that it has turned into one of the most fatal diseases in the world. On time diagnosis of this disease can be effective in the prevention of its bad effects, its control and remedy. With technology advancement and changing many issues in software industry, doctors have developed a tendency towards intelligent systems for better diagnosis. Thus, in this paper, we have diagnosed liver sickness using fuzzy logic by obtaining important laboratory parameters. We have used two types of triangular membership function and Gussy membership function per 3 membership function for each input and output and also the design of reference table (search) to construct fuzzy heuristic system and we have managed to compare 243 rules. At the end, we were able to reach to 79/83% of accuracy with the appropriate choice of input parameters, the number and type of membership functions.