To investigate the influence of negative moment zone cracks on the dynamic performance of corrugated steel web composite continuous girder bridges under vehicular loading, a nonlinear vehicle-bridge coupled vibration model was developed based on the ANSYS finite element platform. An open crack damage function was employed to simulate the cracking behavior of concrete in the negative moment region, and the dynamic response of the bridge under vehicle loads was obtained using the fully transient Newmark-β implicit integration method. The effects of crack depth (α) and damage zone length (β) on the bridge’s natural frequency, mid-span displacement, impact factor, and peak strain at critical connection regions were systematically analyzed. In addition, the coupling effect of road surface irregularities was further evaluated. The results indicate that both crack parameters α and β lead to a reduction in natural frequency and an increase in mid-span displacement and impact factor, with a more pronounced influence observed for β. Furthermore, significant amplification of peak strain is found at the deck-to-girder connections. The presence of surface irregularities, when coupled with concrete cracking in the negative moment zone, results in a notable increase in vertical displacement and acceleration responses, thereby accelerating the degradation of structural performance.