Guess it helps to the read the documentation.😮this forum address the issue first:http://forums.arcgis.com/threads/45825-IIS-Web-Adaptor-Install-Error?p=225384#post225384but my install solution: C:\Users\Administrator>msiexec /I D:\WebAdaptor\IIS\setup.msi WEBSITE_ID=1 VDIRNAME=ags /qbRun this command from the command line to uninstall:msiexec /x {11CCA428-4679-4D79-ADC0-A13F43290ACF} /qbUninstalling additional instances silentlyTo uninstall additional instances of the ArcGIS Web Adaptor (IIS) silently, replace the above product code with the product code of the instance to be uninstalled. Product codes for ArcGIS Web Adaptor (IIS) instances are listed below. The product codes are listed in the same order as the instances installed on your system. For example, the first instance created is the first product code listed below:???{F2D4A6C5-E11F-4FEF-A240-5F2BA22F6418}???{DF32A6BA-A260-4BCD-B59A-4CEB4173B2D8}???{0CF52969-7F17-4F85-82FF-C658F3DC5F6E}???{8E4D5C3B-B54C-4CC5-9A5F-3EC0C6BF64F0}???{0329B7AD-D457-42F2-B97E-BBAE26D54329}???{38A627D7-01C7-4E3F-945D-3CD4CDF14BE5}???{635C3AE6-F3F1-434D-B1E7-B12CE91AD83F}???{39BE94C5-8146-4560-A54E-859979624ACF}???{1506767A-988E-44EB-A733-E5B8BFFBE81E}???{BFA02DB7-9E55-4179-88AC-D2C1B9802096}