DiffMerge官方提供的方法在Windows系统下实现无效。。 Google了个更简便的方法，亲测有效，

1、下载DiffMerge

http://sourcegear.com/diffmerge/downloads.php，楼主选择的是 Windows Installer (64bit)，安装直接下一步，这一版只能安装在C盘

2、创建启动DiffMerge脚本

1）在Git的安装路径的\cmd路径下创建以下两个脚本

(如何创建：先创建TXT，粘贴进去，再改txt名字为.sh的脚本名字)
注意：前面的路径名为安装后的DiffMerge.exe的实际路径名，不然git就找不到了，楼主的为”C:/Program Files/SourceGear/Common/DiffMerge/sgdm.exe”

（1）git-difftool-diffmerge-wrapper.sh

# place this file in the Windows Git installation directory /cmd folder
# be sure to add the ../cmd folder to the Path environment variable

# diff is called by git with 7 parameters:
# path old-file old-hex old-mode new-file new-hex new-mode

"C:/Program Files (x86)/SourceGear/DiffMerge/DiffMerge.exe" "$1" "$2" | cat

（2）git-mergetool-diffmerge-wrapper.sh

# place this file in the Windows Git installation directory /cmd folder
# be sure to add the ../cmd folder to the Path environment variable

# passing the following parameters to mergetool:
# local base remote merge_result

"C:/Program Files (x86)/SourceGear/DiffMerge/DiffMerge.exe" "$1" "$2" "$3" --result="$4" --title1="Mine" --title2="Merge" --title3="Theirs"

• 2）将\cmd设置环境变量，方便找

  

  3、黑掉Git配置文件

  找到.gitconfig文件（路径在Windows“用户”路径下），

  
  TXT编辑，相关内容用下面的替换

  [merge]
      tool = diffmerge
  [diff]
      tool = diffmerge
  [mergetool]
      keepBackup = false
  [mergetool "diffmerge"]
      cmd = git-mergetool-diffmerge-wrapper.sh "$LOCAL" "$BASE" "$REMOTE" "$MERGED"
  [difftool "diffmerge"]
      cmd = git-difftool-diffmerge-wrapper.sh "$LOCAL" "$REMOTE"

  • 4、OK

    当merge出现冲突的时候，输入
    git mergetool
    diffmerge就出来啦