This paper aims to find out the difference of human photoplehysmography (PPG) morphological parameter between in normal oxygen concentration regions and in low oxygen level environments. We implemented an experiment with a normobaric hypoxic chamber which generalized low oxygen level environment of 13.4% (equivalent to the altitude of 3600 m). The experiment contained two sections—10 minutes short exposure and a night of sleep. Fingertip PPG signal was recorded in the whole process. We carried out a comparative analysis for each subject in normal and hypoxic conditions. Result showed that the average values in normoxic environment and hypoxic conditions for short exposure were 0.3456 and 0.3861 respectively, and for sleep were 0.3081 and 0.3419 respectively. Significance level p were both less than 0.05. Variations of PPG waveform parameter reflect the changed peripheral vascular resistance. In hypoxic environment, the raised value tallied with the physiological mechanism that hypoxic exposure increases peripheral vascular resistance. And this phenomenon happened since the beginning of hypoxia and could last for at least a night.