Objective: To investigate the situation and risk factors of morning blood pressure surge by analyzing of 24h dynamic blood pressure in the elderly patients with COPD and primary hypertension undergoing invasive mechanical ventilation. Methods:79 cases of elderly patients with COPD and primary hypertension under invasive mechanical ventilation( SIMV ventilation mode, PEEP≤5cmH2O) were selected in the respiratory intensive care unit of a top three hospital in Tianjin. EKG and APACHEⅡ were used to monitor 24h ambulatory blood pressure and to assess condition of the patients. Results: The average of 24h systolic blood pressure(24h SBP) was 151.20±5.69 mmHg，and the average of 24h diastolic pressure(24h DBP) was 76.39±6.42 mmHg. About 72.2% of the patients have high-morning blood pressure surge, and the average of morning blood pressure surge was 38.82±8.78 mmHg. Single factor analysis showed that there were differences in morning blood pressure surge between patients with different age and different APACHE II score, and there was statistic difference in the average of 24h SBP and D-SBP(diurnal systolic blood pressure) between the patients with morning surge arose or not；Logistic regression analysis showed that APACHE II score, the average of 24h SBP and D-SBP were the influence factors of the morning surge arose, the three could explain 82.3% of the blood pressure variation.Conclusion: The proportion of morning surge cases in the elderly patients with COPD and primary hypertension undergoing invasive ventilation is higher. We should pay more attention on the patients with critical condition of morning surge arose in order to relive the damages to target organ.