Objective To study the effect of the reinforcing and reducing method of acupuncture reported in first Chapter the Nine Needles and Twelve Yuan of the Miraculous Pivot on interstitial fluid pressure (IFP) in subcutaneous tissue of minipig, and to investigate its biomechanical mechanism of regulating the interstitial fluid. Methods Nine healthy minipigs were randomly selected for reinforcing method (pull or press) and reducing method (wave a big pinhole), and tested on soft skin tissues of the abdomen. The IFP in the normal state (NS), the low volume (LV) state (by extracting interstitial fluid) and the high volume (HV) state (by injecting saline solution) was measured before and after acupuncture. Results In the normal state, pulling and pressing the needle could obviously increase IFP, while reducing method could significantly decrease IFP, leading to a rapid decrease in 5 min after acupuncture. In the LV state, pulling and pressing the needle could increase IFP. However, in 10 min after acupuncture, the descend rates of IFP were relatively slower. In the HV state, the reducing method could significantly decrease IFP, and the changing trend in 5 min after acupuncture was different from that of the control group. Conclusions The reinforcing and reducing method of acupuncture could increase or decrease IFP, which proved that the acupuncture method could regulate IFP in the opposite direction. The research findings provide a new scientific basis for using reinforcing and reducing method of acupuncture in clinic.