Abstract: Objective: To explore the longitudinal dynamic relationships of mutual interactions between anxiety and depression and identify optimal intervention targets in patients with nasopharyngeal carcinoma undergoing concurrent chemoradiotherapy. Methods: From October 2024 to October 2025, a four-wave follow-up survey was conducted among 424 patients with nasopharyngeal carcinoma undergoing concurrent chemoradiotherapy using the generalized anxiety disorder-7(GAD-7) and patient health questionnaire-9(PHQ-9)(T1: at admission following diagnosis; T2: at the completion of the first radiotherapy session; T3: at the completion of the 15th radiotherapy session; T4: at the completion of the 30th radiotherapy session). Data analysis was performed using the cross-lagged panel network model. Results: The anxiety scores of patients with nasopharyngeal carcinoma undergoing concurrent chemoradiotherapy at the four follow-up waves were 3.04±2.90, 3.18±2.59, 4.45±3.54, and 4.87±3.79, respectively; the depression scores were 3.65±2.99, 4.42±3.02, 6.74±4.59, and 7.10±5.09, respectively, showing an upward trend. Cross-lagged panel network analysis revealed that "feeling like a failure" had a positive predictive effect on "uncontrollable worry" at the T1-T2 interval(edge weight=0.25); "suicidal ideation" had a positive predictive effect on "irritability" at the T2-T3 interval(edge weight=0.42); and "feeling afraid" had a positive predictive effect on "fatigue" at the T3-T4 interval(edge weight=0.19). "Activity impairment" exhibited the greatest bridge expected influence(BEI=1.31) in the cross-lagged network between T2 and T3, serving as the central node linking the co-occurrence and mutual transition of anxiety and depression. Conclusion: Anxiety and depression in patients with nasopharyngeal carcinoma exhibit dynamic predictive relationships across different radiotherapy phases. "Activity impairment" may serve as a potential intervention target, enabling medical staff to implement precise interventions based on bridge central symptoms.