最大也只能500M。
原文
Saving a list as a template is an easy way of transferring data from one place to another in SharePoint. By default, however, the maximum size of list templates in WSS 3.0 and MOSS 2007 is 10MB.

If you try to save the list as a template that is larger than this you will get the following error:

The list is too large to save as a template. The size of a template cannot exceed 10485760 bytes.

To increase the maximum size, simply run the following stsadm command (from the C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\BIN directory) replacing the propertyvalue to the new maximum size (in bytes):

stsadm -o setproperty -propertyname max-template-document-size -propertyvalue 50000000

Points to note:

• The propertyvalue parameter is in bytes, so the example above will increase the maximum size to approx 50MB.
• There is a hard limit of 500MB so the value must be less than 524288000 or you will get an error when saving the list as a template.
• The above increases the maximum size of both site and list templates.