Objective To explore the effect of rehabilitation nursing under the guidance of precision nursing theory on cardiac rehabilitation and psychological state in patients with myocardial infarction after PCI intervention. Methods A total of 82 patients with myocardial infarction after PCI intervention who were treated from February 2019 to February 2021 were selected as the research objects, and divided into the control group and the observation group with 41 cases in each group by random number table method. The control group was received routine nursing intervention, while the observation group was received rehabilitation nursing intervention under the guidance of precision nursing theory on the basis of the control group. The cardiac function indexes and psychological state scores of the two groups were compared. Results After intervention, the levels of LVEF indexes in the observation group were higher than those in the control group, and the levels of cTnI and NT-proBNP indexes were lower than those in the control group, the difference was statistically significant (P＜0.05); the HAMA and HAMD scores of the observation group were lower than those of the control group, the difference was statistically significant (P＜0.05). Conclusion Rehabilitation nursing under the guidance of precision nursing theory can not only promote the recovery of cardiac function in patients with myocardial infarction after PCI intervention, but also improve their psychological state.