To address the fracturing issue of tungsten alloy balance weight in diesel engine, the failure mechanism was analyzed through microstructural characterization, chemical composition testing, and mechanical property evaluation. The results indicated that the failure balance weight exhibited poor sintered density with matrix porosity and weak metallurgical bonding between tungsten particles and the binder phase, resulting in insufficient material strength. Fractographic analysis revealed predominant intergranular fracture characteristics, demonstrating that cracks initiated and propagated along tungsten-tungsten interfaces and tungsten-binder interfaces when operational loads exceeded the material strength limit, ultimately causing overload fracture of balance weight. The research proposed and validated preventive measures based on the identified failure mechanism, providing the valuable references for the design and failure analysis of diesel engine balance weights.