Objective To explore the experiences of catheterization laboratory nurses in recognizing and respond-ing to clinical deterioration during emergency percutaneous coronary intervention in patients with ST-segment eleva-tion myocardial infarction，providing evidence for optimizing nurses’ clinical judgment and improving patient out-comes. Methods Guided by Tanner’s Clinical Judgment Model，a phenomenological approach was used. Semi-structured interviews were conducted with thirteen catheterization laboratory nurses in a tertiary hospital in Nanjing，China，from January to February 2025. Interview data were analyzed using Colaizzi’s seven-step method. Results Six themes and eight subthemes were identified：patient observation（including the salience of objective indicators and the predictive value of symptoms and signs）；valuing experience（trusting intuition and integrating knowledge）；information synthesis（clinical reasoning and filtering interference）；prioritization of interventions；team cohesion （collaboration and coordination，execution and review）；and reflective growth. Conclusion The identification and responding of clinical deterioration by catheterization laboratory nurses during emergency percutaneous coronary intervention constitute a dynamic process characterized by the close integration of theoretical knowledge，intuitive judgment，rapid decision-making，and team collaboration. Nursing managers should establish training systems that integrate objective indicators with non-quantifiable cues，promote the transformation of nurses’ experiential knowledge，and enhance clinical judgment capacity through clearly defined interprofessional roles and responsibilities，optimized collaborative deci-sion-making processes and reflective mechanisms，comprehensively enhanced nurses’ clinical judgment abilities，thereby ensuring patient safety.