Coronary stent is of a micro cylindrical net structure. In this paper stability and dynamic deforming process for structure of coronary artery stents in percutaneous coronary intervention (PCI) was studied by measurements of stent deformation under pressure and theoretical analysis. In PCI, a stent has two stages of loading (1) the stage stent in inflated, and (2) the stage stent is left, and is under the pressure of the shrinkage of the artery. For the first stage, the change of the stent diameter was measured by the observation with a microscope. Load-displacement curves of the stent in the inflation process were got. The maximum deformation rate of the inflating stent was 2.0 mm/s at the right end of the stent at the inflating time 15.5 s. In the second stage, the buckling behavior of the stent was studied. An "Intelligent Electronic Measurement Apparatus" was used for the buckling test of stents. Some new buckling phenomena of multi-buckling were revealed in the tests. These results will be important for the research of the stent properties. (c) 2005 Elsevier B.V. All rights reserved.