Thrombus fragmentation is a leading cause of poor outcomes in the treatment of acute ischemic stroke with endovascular thrombectomy (EVT). A mechanistic understanding of thrombus fracture is essential for realistic simulation of thrombus behavior during EVT. Existing thrombus fragmentation models are generally not tailored to thrombus characteristics, such as nonlinear large deformations and toughening due to fibrin fiber alignment. In this study, we establish a computational framework based on the phase-field (PF) method to investigate fracture initiation and propagation in thrombi of different compositions under controlled loading conditions. We extend the framework to finite strains and couple the PF evolution with a fiber-based hyperelastic constitutive model for thrombus [1] through a user material subroutine (UMAT) in Abaqus [2]. An energy decomposition based on fiber stretch is introduced to prevent non-physical crack growth under compressive loadings. Constitutive parameters are calibrated using unconfined compression and tensile-to-failure experimental data on thrombus analogues with varying compositions. Fracture simulations are then performed under mode-I loading using compact tension specimens and under mixed-mode conditions using lap-shear configurations. Preliminary results reveal a clear sensitivity to the chosen PF formulation (Fig. 1a). Models incorporating a damage threshold (TMs) delay fracture onset but require careful calibration, as the threshold depends on other material parameters. In contrast, threshold-free formulations such as AT2 exhibit early softening, leading to a reduced apparent material strength compared to experimental observations. Fracture simulations suggest that the proposed framework can capture crack initiation and propagation direction under mode-I and mixed-mode conditions (Fig. 1b). Future developments will include validation against fracture experiments on thrombus analogues of different compositions.