The principle of multi-cluster fracturing in tight reservoirs is illustrated in Figure 1. This method involves creating multiple hydraulic fracture networks in various blocks within the reservoir by strategically establishing multiple perforation positions and adjusting the fluid distribution across different clusters. The overarching objective is to enhance reservoir permeability and facilitate efficient development. Early reservoir fracturing simulations were mainly achieved through finite element methods. Subsequently, considering that reservoir rocks are a discontinuous medium, some new numerical simulation methods were proposed successively, such as the extended finite element method [18], particle flow dispersion element method [19; 20], block discrete element method [2], discontinuous element method [21], finite discrete element method (FDEM) [22], etc. These methods make it possible to predict the fracturing construction effect of the target reservoir more accurately, but they have different advantages and limitations. For example, the extended finite element method uses virtual functions to construct a discontinuous displacement field, which can simulate the phenomenon of fracture deflection and propagation inside the element, but it is difficult to simulate the effects of natural fractures and other factors such as fracture bifurcation. The particle flow dispersion element method has an excellent performance in simulating reservoir fracturing at the micro-scale, but it usually assumes that the reservoir is composed of particles, which has great computational limitations and is no longer suitable for reservoir-scale simulation analysis [23; 24]. The block discrete element method and finite discrete element method developed in recent years have effectively solved the scale limitations, thus enabling better simulation and evaluation of reservoir fracturing from micro- to macro-scales. Among them, the finite discrete element method [25] assumes that the reservoir is composed of rock blocks and their fractured interfaces (Figure 1). The rock block elements are used to simulate the deformation characteristics of the reservoir matrix during the fracturing process, and the interface elements are used to simulate the propagation of artificial fractures in the reservoir. Meanwhile, with years of development, the characteristics of natural fractures in reservoirs can be described by changing parameters such as the strength and stiffness of different interface elements, thereby achieving fracturing simulation on reservoirs containing natural fractures. Based on the FDEM method, [PERSON] et al. [26] conducted a hydraulic fracturing inversion simulation study considering the natural bedding/fracture interfaces in rocks. Their findings confirmed the viability of utilizing the FDEM to simulate fracture formation in rocks containing such natural features. Additionally, they developed hydraulic fracturing models for reservoir areas considering various heterogeneous structures and conducted a detailed analysis on the impact of factors like natural discrete fractures and large embedded rock blocks on the propagation of hydraulic fractures [27]. Therefore, conducting a simulation study on fracturing in fractured reservoirs using the FDEM proves to be an effective method for unveiling the propagation behavior of hydraulic fractures in reservoir rocks containing natural fractures. Based on the finite discrete element method (FDEM), this paper establishes a three-dimensional multi-cluster fracturing simulation model considering the number of natural fractures. The conventional quantitative parameters such as fracture area, fracture length, and maximum fracture aperture were used to systematically analyze the expansion law of artificial fractures under the combined influence of natural fractures and multi-cluster fracturing. The numerical model, the comparative analysis results, and the conclusion are presented in Sections 2, 3, and 4, respectively. Figure 1: Schematic diagram of reservoir multi-cluster fracturing and FDEM principle.