<正> The interaction of heavy ions with solids produces a latent track of primary damage along ion path. In order to study some problems about the track cores, we must reveal and enlarge the cores by chemical etching. To acquire a very small pore, a high sensitive etching set-up is required.Our lab devised a high sensitive etching system in 2002. Fig.1 shows the diagram of the experimental setup. The set-up is composed of four parts: temperature controller, etching trough, electricity supplier and