In this paper, we apply the micropipette to reduce the surface area of the rabbit aorta, and the relationship between the fractional area change of the aortic surface and the negative pressure in the pipette is studied. The experimental results for seven rabbit thoracic aortas show that the relationship can be expressed as P = K x (ec alpha- 1), where P is the negative pressure applied to the aorta surface through the micropipette, alpha is the fractional area change of the aortic surface, K and C are constants. For the rabbit thoracic aorta, the value of K is between 5 and 17 kPa, with a mean of 8.66 kPa the value of C is between 8 and 19, with a mean of 12.11.