The circadian rhythm of defensive qi circulation appears to be inconsistent in Huangdi Neijing Lingshu Circulation of Defensive Qi.This paper analyzed this issue.Through the method of comparison and mutual verification of the original text of Huangdi Neijing and summarizing and analyzing various viewpoints,this paper discussed and compared relevant text such as the number of underwater engravings,the speed of the nutrient qi and defensive qi,and the boundary between muscles of the meridians in Huangdi Neijing,and put forward reverse hypotheses for contradictions,and then further analyzed other question points.It was found that underwater engravings may have 2 meanings of time point and time period.Then underwater engravings indicate that the qi circulation time conflicts during the time period,and the speed of qi circulation is irregular and uneven during the daytime.Six yang of qi circulation may represent six yang boundary between muscles,and there may be hidden paths outside the existing qi circulation routes.In the end,it was concluded that 25 laps each day and night may be the main way of defensive qi circulation.In the day time,it circulates in six yang boundary between muscles and yin level boundary between muscles.In addition to the main path,there are four ends,bone joints,collaterals,tendon and other parts also have defensive qi distribution.In the night time,it circulates in five zang-organs,and involves six fu-organs,while qi location in a certain moment underwater may refer to the boundary between muscles of specific meridian with appearance of defensive qi at a certain point in the day.In case of disorder,it starts with the sunrise and wakes up,with a moment as the four ke.Taiyang,Shaoyang,Yangming and Yin are divided into four parts for cyclic timing.The meat corresponding to acupuncture is divided according to the specific time law of waiting for qi,and acupuncture treatment is carried out according to the deficiency and excess to meet the tonic and diarrhea.