The purpose of this research was fabrication and characterization of Al-0.5wt%Ti-0.3wt%Zr-B 4 C composite via pseudo-in-situ stir casting. In this process, 5 percent of unpreheated B 4 C particles with size over 75 µm and approximate average size 150 µm are introduced into the melt and in the first step the effect speed and time of stirring on efficiency of particle remained in the as-cast microstructure, particles distribution, the resulted mechanical properties and density were evaluated. Results of the first step of this research indicate that between two stirring speeds of 600 and 700 rpm and stirring times of 5, 10 and 15 minutes, sample fabricated by 700 rpm stirring speed and stirring time of 15 minutes had the best condition from the amount of the remained particles in the as-cast microstructure of the composite and the particles distribution point of view. On the other hand, low thermal shock resistance of B 4 C particles and introduction of these relatively large particles into the melt without preheating caused breakage and creation of fine B 4 C particles with size less than 20 µm in the microstructure. In the second step, for reducing occurrence probability of particle rejection phenomenon and porosity defects, effect of the two parameters i.e. position of stirrer and schedule of particles addition on efficiency of remained particles in the as-cast microstructure, particles distribution, resulted mechanical properties and density were evaluated on the sample with the best condition of the first step (stirring speed of 700 rpm and stirring time of 15 minutes). Results of the second step of this research indicated that positioning the stirrer near the bottom of the crucible (distance of stirrer from the bottom of the crucible equal to 12±3 mm) resulted in porosity reduction and higher mechanical properties and on the other hand had nearly no effect on amount of remained particles in the as-cast microstructure and particle distribution. Totally from the results of the two casting steps it can be concluded that the best condition for the evaluated parameters are stirring speed of 700 rpm, total stirring time of 15 minutes, distance of stirrer from bottom of crucible equal to 12±3 mm and the schedule of particle addition included 10 minutes for adding time and 5 minutes for stirring after that. Keywords : Pseudo-in-situ stir casting, Aluminum-B 4 C composite, reinforcement particles distribution, Image analysis