To produce polymer matrix composites, direct printing can be used without the need to make filament. This technology is known as liquid deposition modeling (LDM). In this process, polymer materials mixed with microparticles enter the printer cylinder in the form of granules and after reaching the melting temperature, they are printed on the machine bed. In this research, polymer-based composites made of polypropylene were produced by adding copper microparticles using LDM technology. For this purpose, experimental tests were designed based on a full factorial design. In the following, the composite samples conforming to the geometry of the tensile test sample were printed under certain settings of the input variables including: layer thickness, microparticle size and weight percentage of microparticles, and the yield strength and flexibility of the samples were evaluated based on ANOVA. The results of the statistical analysis showed that the coefficient of variation of the regression models to predict the yield strength and flexibility of the samples are equal to 98.85 % and 98.63%, respectively. Also, dual-objective optimization was performed using the desirability method in order to maximize the response parameters, and the optimal combination of input variables was determined with the desirability value of 96.1%. The optimal values of layer thickness, microparticle size and weight percentage of microparticles were extracted as equal to 180 micron, 45 micron and 10% respectively.