The factors that influence metacognitive judgments often appear in combination, rather than in isolation. The multi-cue utilization model proposes that individuals often make use of multiple cues when making judgments. Previous studies have focused on the integration of intrinsic and extrinsic cues, while the current investigation examines the integration and influence of intrinsic cues and mnemonic cues. Judgment of confidence is a common form of metacognitive judgment. In this study, 37 college students completed Raven’s Progressive Matrices and made judgments of confidence. We used the cross-level moderated mediation model to explore the impact of item difficulty on confidence judgments. Our results indicated that item difficulty negatively predicts the level of confidence. Item difficulty has an impact on the confidence evaluation by altering the processing fluency of intermediate variables. The joint effect of intrinsic cue item difficulty and mnemonic cue processing fluency influences confidence judgments. Additionally, we found that intelligence moderates the effect of difficulty on processing fluency across levels. Specifically, individuals with higher intelligence exhibited lower fluency on difficult tasks and higher fluency on simple tasks than individuals with lower intelligence. These findings expand on the multi-cue utilization model and integrate the influence mechanism of intrinsic and mnemonic cues on confidence judgments. Finally, we propose and verify a cross-level moderated mediation model that explains how item difficulty affects confidence judgments.