Abstract: Objective To explore the clinical effects of nursing measures in phase Ⅰ cardiopulmonary rehabilitation on cardiopulmonary function in patients undergoing coronary artery bypass grafting(CABG) on the basis of precision nursing theory. Methods A total of 114 patients with CABG who were treated in our hospital from August 2017 to April 2018 were selected by convenient sampling method. The patients were divided into experimental group and control group by random number grouping, 57 cases in each group. The patients in the control group underwent routine treatment and nursing. The experimental group implemented the phase Ⅰ cardiopulmonary rehabilitation care measures under the theory of precision nursing, including advanced sports rehabilitation program, respiratory exercise and health education in cardiac rehabilitation. Both groups were nursed for one month. The patients in the two groups were examined by ultrasound before operation and before discharge, and evaluated by 6-minute walking test(6 MWT) before discharge. Results There were significant differences in left ventricular diameter, left ventricular ejection fraction, 6 MWT, and maximum oxygen uptake(VO_{2 max}) between the experimental group and the control group[(43.87±6.84)mm,(71.32±8.37)%,(265.31±75.27)m,(14.76±3.64)mL/(kg·min) vs.(49.36±6.51)mm,(66.93±8.97)%,(235.48±60.54)m,(10.97±2.35)mL/(kg·min), all P<0.05)]. Conclusion Under the theory of precision nursing, phase Ⅰ cardiopulmonary rehabilitation can significantly improve the maximum oxygen uptake of CABG patients, enhance the cardiopulmonary function and the actual endurance of aerobic exercise, which is worthy of clinical promotion.