Objective To explore the effectiveness of the diffusion of innovation theory in com-bination with multidisciplinary nursing collaboration in intervention for patients with severe pneumonia complicated by heart failure.Methods A total of 120 patients with severe pneumonia complicated by heart failure admitted between April 2021 and April 2024 were enrolled and randomly divided into observation group(n=60)and control group(n=60)using a random black-and-white ball method.The control group received conventional nursing intervention,while the observation group received an intervention model combining the diffusion of innovations theory with multidisciplinary collaboration on top of the conventional nursing.Rehabilitation outcomes(time to control of pulmonary inflammation,time to resolution of cough and expectoration,length of hospital stay)and post-intervention cardiac function[left ventricular ejection fraction(LVEF),left ventricular end-systolic volume(LVESV)]were compared between the two groups.The Minnesota Living with Heart Failure Questionnaire(MLHFQ)was used to assess quality of life,and the Self-Care Heart Failure Index(SCHFI)was used to evaluate self-care behaviors.Complications were compared between the two groups,and cost-effectiveness was analyzed(patient medical expenses and re-hospitalization rates).Results The observation group had shorter time to resolution of cough and expectoration,control of pulmonary inflammation,and length of hospital stay compared with the control group,with statistically significant differences(P＜0.05).After intervention,LVEF increased in both groups compared with pre-intervention lev-els,and was higher in the observation group than in the control group,with a statistically significant difference(P＜0.05);ESV decreased in both groups compared with pre-intervention levels,and was lower in the observation group than in the control group,with a statistically significant difference(P＜0.05).After intervention,physiological,emotional,and social functioning scores in the MLHFQ decreased in both groups compared with pre-intervention levels,and were lower in the ob-servation group than in the control group,with statistically significant differences(P＜0.05).After intervention,scores for self-care maintenance,self-care management,and self-care confidence in the SCHFI increased in both groups,and were higher in the observation group than in the control group,with statistically significant differences(P＜0.05).There was no statistically significant difference in the incidence of complications between the two groups(P＞0.05).Conclusion The combination of the diffusion of innovations theory and multidisciplinary collaboration nursing model can accelerate the rehabilitation process in patients with severe pneumonia complicated by heart fail-ure,improve their quality of life,and effectively enhance their self-care abilities.