DiffMerge官方提供的方法在Windows系統下實現無效。。 Google了個更簡便的方法，親測有效，

1、下載DiffMerge

2、建立啟動DiffMerge指令碼

1）在Git的安裝路徑的\cmd路徑下建立以下兩個指令碼

(如何建立：先建立TXT，貼上進去，再改txt名字為.sh的指令碼名字)
注意：前面的路徑名為安裝後的DiffMerge.exe的實際路徑名，不然git就找不到了，樓主的為”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）將\cmd設定環境變數，方便找

3、黑掉Git配置檔案

找到.gitconfig檔案（路徑在Windows“使用者”路徑下），

TXT編輯，相關內容用下面的替換

[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

當merge出現衝突的時候，輸入
git mergetool
diffmerge就出來啦