http://igaozh.iteye.com/blog/1674071
Just hold down theShiftkey while you right click on the file. Then select→. In the following dialog, specify the URL in the repository with which you want to compare your local file to.
詳見：http://tortoisesvn.net/docs/nightly/TortoiseSVN_en/tsvn-dug-diff.html
File Differences
- Local changes
If you want to see what changes you have made in your working copy, just use the explorer context menu and select → .
- Difference to another branch/tag
If you want to see what has changed on trunk (if you are working on a branch) or on a specific branch (if you are working on trunk), you can use the explorer context menu. Just hold down the Shift key while you right click on the file. Then select → . In the following dialog, specify the URL in the repository with which you want to compare your local file to.
You can also use the repository browser and select two trees to diff, perhaps two tags, or a branch/tag and trunk. The context menu there allows you to compare them using . Read more in the section called “Comparing Folders”.
- Difference from a previous revision
If you want to see the difference between a particular revision and your working copy, use the Revision Log dialog, select the revision of interest, then select from the context menu.
If you want to see the difference between the last committed revision and your working copy, assuming that the working copy hasn't been modified, just right click on the file. Then select → . This will perform a diff between the revision before the last-commit-date (as recorded in your working copy) and the working BASE. This shows you the last change made to that file to bring it to the state you now see in your working copy. It will not show changes newer than your working copy.
- Difference between two previous revisions
If you want to see the difference between two revisions which are already committed, use the Revision Log dialog and select the two revisions you want to compare (using the usual Ctrl-modifier). Then select from the context menu.
If you did this from the revision log for a folder, a Compare Revisions dialog appears, showing a list of changed files in that folder. Read more in the section called “Comparing Folders”.
- All changes made in a commit
If you want to see the changes made to all files in a particular revision in one view, you can use Unified-Diff output (GNU patch format). This shows only the differences with a few lines of context. It is harder to read than a visual file compare, but will show all the changes together. From the Revision Log dialog select the revision of interest, then select from the context menu.
- Difference between files
If you want to see the differences between two different files, you can do that directly in explorer by selecting both files (using the usual Ctrl-modifier). Then from the explorer context menu select → .
- Difference between WC file/folder and a URL
If you want to see the differences between a file in your working copy, and a file in any Subversion repository, you can do that directly in explorer by selecting the file then holding down the Shift key whilst right clicking to obtain the context menu. Select → . You can do the same thing for a working copy folder. TortoiseMerge shows these differences in the same way as it shows a patch file - a list of changed files which you can view one at a time.
- Difference with blame information
If you want to see not only the differences but also the author, revision and date that changes were made, you can combine the diff and blame reports from within the revision log dialog. Read the section called “Blame Differences” for more detail.
- Difference between folders
The built-in tools supplied with TortoiseSVN do not support viewing differences between directory hierarchies. But if you have an external tool which does support that feature, you can use that instead. In the section called “External Diff/Merge Tools” we tell you about some tools which we have used.
If you have configured a third party diff tool, you can use Shift when selecting the Diff command to use the alternate tool. Read the section called “External Program Settings” to find out about configuring other diff tools.