###### Abstract  
In the research on the influence of pore structure on the macroscopic mechanical properties of concrete, the experimental method cannot realize the accurate control of the pore structure parameters, and the research based on the numerical simulation method is insufficient in the scientific simulation and parameterization of the complex pore structure. A new numerical concrete modeling method is proposed, which introduces the total porosity, pore gradation, pore size, and sub-porosity of each gradation segment to realize the accurate simulation and parameterization of the pore structure. Based on the control variable method, 25 concrete mesoscopic models with the same aggregate structure and different pore structures are established, and uniaxial tensile experiments are performed. The pore structure accelerates the process of damage expansion from the periphery to the center of the specimen and makes the damage inside the cement mortar more localized. There are obvious exponential function relationships of three pairs: total porosity and elastic modulus, PSSA and elastic modulus, and tensile strength and total porosity. There is an obvious quadratic polynomial function relationship between tensile strength and specific surface area. For specimens with the same aggregate structure and total porosity, the elastic modulus increases with the increase of the macropore content, and the tensile strength and elastic modulus are basically not affected by the average pore radius. The effect of pore space distribution and sub-porosity on peak strain is greater than that of total porosity, but no obvious regularity is shown. For pores with a radius in the range of 0.15-0.8 mm, the smaller the pores, the greater the effect of their porosity on the elastic modulus and tensile strength, and the less effect on the peak strain. the pore structure parameters of concrete, such as porosity, pore size, and pore distribution, and then study the relationship between the pore structure parameters and macroscopic mechanical properties. For example, [PERSON] [6] and [PERSON] [9] measured the area percentage of pores in different pore size ranges by optical microscope and established the relationship between compressive strength and graded porosity. [PERSON] [10] and [PERSON] [11] studied the effects of pore distribution and pore size on the durability and strength of concrete by the mercury intrusion method. [PERSON] et al. [12] indirectly established the relationship between the pore structure and the macroscopic mechanical properties of concrete by adding air-entraining agents to concrete specimens. However, there is an obvious defect of the experimental method in establishing the relationship between pore structure parameters and concrete mechanical properties; that is, it is almost impossible to change the pore structure alone without changing the aggregate structure. This makes the change of concrete mechanical properties not only produced by the change of pore structure, but also by the change of aggregate structure. An effective way to solve this problem is to establish mesoscale finite element models of concrete and use numerical analysis method to conduct research in this area. There are two main approaches to generate mesoscale models of concrete: the image-based modeling method and the parametric modeling method. The former builds the model completely based on the images obtained from the test, which is its advantage; that is, it can accurately reflect the size, shape, and distribution of concrete mesoscopic components [13; 14; 15; 16; 17; 18; 19; 20]. However, it has its disadvantage when it is applied to study the relationship between the pore structure parameters and the mechanical properties of concrete; like the experimental method, it is impossible to change the pore structure alone without changing the aggregate structure.