If you can't access Taobao on a mobile network, there may be the following reasons:

1. Poor mobile network signal quality: Taobao needs to be accessed through the network. If your mobile network signal quality is poor, it may cause slow access or inaccessibility. You can try to find a place with better network signal strength, or switch to a Wi-Fi network to access.

2. Taobao server failure: If the Taobao server fails, it may cause Taobao to be unable to use normally. You can try to wait for a while, or search to see if other users have encountered the same problem.

3. Taobao software version is outdated: If your Taobao software version is too old, it may cause Taobao to be unable to use normally. You can try to update to the latest version, or uninstall and reinstall Taobao.

4. Mobile system problem: In some cases, mobile network access problems may be caused by problems with your mobile operating system. You can try restarting your phone, clearing the cache, or restoring factory settings to solve the problem.

If you have tried the above methods and still cannot use Taobao mobile network, please try to contact the network operator or Taobao customer service for further assistance.