This study explores internal linkages among depressive, anxiety, and acute stress symptoms in 2021 Henan floods victims during the disaster. Moreover, the interaction between instant flood exposure (IFE) and symptoms were testified. We conducted a survey from July 20 to August 6, 2021, when floods occurred in Henan. We employ convenience sampling to capture the immediate reaction of those (N = 714) exposed to the floods. We use self-reported survey answers to assess IFE and depressive, anxiety, and acute stress symptoms. We adopt a psychological network approach to analyze the internal linkages among symptoms and linkages between IFE and symptoms. Results revealed that: First, the strongest relationship between symptoms within each network model remains stable irrespective of whether we control for IFE; however, the strongest edge within depressive symptom cluster differs between the depression network and the depressive-anxiety-acute stress symptom cluster network. The order of central symptoms for depressive symptom cluster, anxiety symptom cluster, and acute stress symptom cluster changes after controlling for IFE. Second, the bridge symptoms of depressive-anxiety-acute stress symptom cluster network remain stable regardless of whether we control for IFE. However, the bridge symptoms of the depressive and acute stress symptoms network vary after controlling for IFE. Third, IFE related to changes in living and family conditions is a crucial factor in linking depressive, anxiety, and acute stress symptoms. Inconsistent results between depressive, anxiety, and acute stress symptom cluster networks and depressive-anxiety-acute stress symptom cluster network reveal that studies employing a network approach should control for potential confounders to avoid omitted variable bias. Sequential psychiatric reactions toward IFE during a disaster imply that pre-disaster community cohesion is crucial for positive coping during the disaster.