Abstarct: Additive manufacturing refers to a set of processes during which a three-dimensional model is designed using a computer and is transformed into a physical part baxsed on the laxyer-by-laxyer placement of materials. Fused deposition modeling (FDM) has been introduced as one of the additive manufacturing methods. In the present research, using this process, standard samples of PETG filament were printed under various combinations of input variables and their mechanical properties were evaluated. In the first phase of the research, using the principles of DOE, the effect of input variables such as laxyer height, nozzle temperature, and printing speed on tensile, impact, and hardness properties of printed parts was studied. For this purpose, the response surface methodology (RSM) and Box-Benken design (BBD) were chosen as the experimental design method. Next, the analysis of variance of the data obtained from tensile, impact and hardness tests were performed. The ANOVA results showed that the square of the printing speed is known as the effective term on the yield strength. Also, interactive terms of the product of the laxyer height and the printing speed, the product of the nozzle temperature and the printing speed and the square of the nozzle temperature were identified as effective terms on the fracture strength. In addition, the first-order term of laxyer height, interactive terms of product of laxyer height and nozzle temperature, product of nozzle temperature and print speed and square of print speed were introduced as effective terms on the impact strength. On the other hand, the optimal values of the input variables were determined with the aim of maximizing the mechanical properties using the desirability method. In order to verify the responses obtained from the optimization process and also measure the accuracy of the regression models, experimental tests were carried out using the optimal conditions of the input variables of the process. The results of the verification tests confirmed the results of the optimization process with a small difference percentage. In the second phase of the research, the effect of input variables such as: filling pattern, orientation of printing and raster angle on tensile and impact properties of printed parts were studied. The results showed that printing the sample using a grid pattern results in an increase in yield strength, ultimate tensile strength and fracture strength. In addition, printing the part on the edge results in increasing the ultimate tensile strength and impact strength. On the other hand, printing the sample under raster angles of 45 degrees and 90 degrees will result in increasing the ultimate tensile strength and impact strength, respectively.