The fish language embedded within PFC2D is used to create irregular aggregate, the numerical model that what we create is analyzed via Using the method of control variables for the influence of biaxial compression failure. The results show that : the main influence of concrete material inhomogeneity is the mean intensity and standard deviation, the higher inhomogeneous degree the lower intensity and the crack space distribution become more disperse; Friction coefficient is the main influence for the shape of stress-strain curve and material intensity, the higher friction coefficient , the greater the bite force between the particles, the greater the residual strength of the curve decline; The formation of rigid contact between particles is caused by the increase of stiffness ratio and connect modulus ,the effect of parallel bond is weaken and high tensile stress and more tension crack are produced , eventually macro performance come from tension crack. It can be helped us make a better choice by studying the mesoscopic mechanics parameters of the concrete numerical simulation and provided the basic reference for building numerical model later.