The blisk of aviation engines, which operate in harsh environments for long periods, is highly susceptible to fatigue cracks in the blades. Due to the blisks’ distinct coupled vibration characteristics and sensitivity to mistuning, the complex vibration mechanisms caused by local, nonlinear structural changes, such as blade cracks, are not well understood. This lack of clarity poses challenges for identifying blade cracks under conditions of stiffness mistuning. This article considers the contact characteristics of fatigue cracks, introduces nonlinear contact forces to simulate the characteristics of fatigue cracks, and, based on a lumped parameter model, studies the vibration response characteristics of cracked blisks under random mistuning conditions. On this basis, a finite element model is established to perform vibration response analysis on cracked blisks under different excitation conditions, exploring the nonlinear characteristics of the blisks caused by cracked blades under various conditions and comparing these with mistuned, intact bladed disks. Based on these nonlinear characteristics, crack-sensitive feature parameters were extracted. Finally, the article analyzes the conditions of fatigue cracks at different stages and blades with multiple cracks. The results show that these crack-sensitive feature parameters can effectively distinguish between cracks and mistuning interference, allowing for the identification and localization of cracked blades.