Abstract: The large-span prestressing truss-string applied to Guangzhou International Conference Exhibition Center is a new-type structure．In this paper‚modern geodetic instruments and technologies were used to monitor the geometric deformation on the spot‚with the aim of investigating the real deformation of the truss-string in different construction periods．Deformation parameters and characteristics of the truss-string in different construction periods were then obtained．The results indicate that the displacement of the truss-string mostly happens in Z direction‚and the deformation at the middle observation point is the biggest．It is also indicated that‚in the tension period‚the actual deformation proves bigger than the theoretical calculation．

Key words: Guangzhou International Conference Exhibition Center, large-span truss-string, geometric deformation, observation