You can merge multiple documents into one document by using the Text from File function in Word, but by doing this, you will lose the format of documents after merged.

1. Create a new Word document you will place the merged documents, and then click Insert > Object > Text from File. See screenshot:

2. In the opening Insert File dialog box, please (1) open the folder containing documents you will merge; (2) select the documents you will merge; and then (3) click the Insert button. See screenshot:

Tip: Holding Ctrl key, you can select multiple documents with clicking them one by one; holding Shift key, you can select multiple adjacent documents with clicking the first one and the last one.

3. If documents you need to merge are saved in different folders, please repeat above Step 1-2 as your need.

Note: You can't order documents in merged file, otherwise you insert them one by one.

Quickly merge multiple Word documents from many folders in bulk, with specified order

Kutools for Word releases a fantastic Merge feature to help users quickly merge multiple Word documents from many folders. This feature will not only reserve original documents' format in merged file, but also merge documents by your specified order.

Alternatively, you can use VBA to merge multiple documents into one in Word.

1. Move all Word documents you will merge into the same folder.

2. Rename the Word documents with a series of sequence names. (1) Right click a document and select Rename from the context menu, and then type a new name, such as Part1; (2) Repeat to rename other documents. See screenshot:

3. Double click to open the document you will place at the beginning of merged file.

4. Press Alt + F11 keys together to open the Microsoft Visual Basic for Application window.

5. Click Insert > Module, and then paste below VBA code into the new Module window;

VBA: merge multiple documents in Word

Sub MergeDocuments()
Application.ScreenUpdating = False
MyPath = ActiveDocument.Path
MyName = Dir(MyPath & "\" & "*.docx")
i = 0
Do While MyName <> ""
If MyName <> ActiveDocument.Name Then
Set wb = Documents.Open(MyPath & "\" & MyName)
Selection.WholeStory
Selection.Copy
Windows(1).Activate
Selection.EndKey Unit:=wdLine
Selection.TypeParagraph
Selection.Paste
i = i + 1
wb.Close False
End If
MyName = Dir
Loop
Application.ScreenUpdating = True
End Sub

Note: This VBA can only merge Word documents whose file extensions are docx. If you need to merge documents (.doc), please replace docx in the code MyName = Dir(MyPath & "\" & "*.docx") to doc.

6.Click the Run button or press F5 key to apply the VBA.

Note: you have to rename the documents with a series of sequence names, otherwise the documents may be disordered or lost in the merged file.

After you installed Kutools for Word, you don't need to create a new blank document, nor put the document into the same folder. With Merge of Kutools, you can quickly merge multiple documents into one in word. Please do as follows:

1. Click Kutools Plus > Merge. See screenshot:

2. In the opening Merge Documents dialog box, please add documents you will merge: (1) Click Add Files button; (2) In the Browse dialog box open folder containing documents you will merge; (3) holding Ctrl or Shift key to select these documents; and then (4) click the OK button. See screenshot:

Tip:
(1) If you need to merge documents that are saved in different folders, please repeat this step to add them one by one;
(2) You can also add all documents saved in one folder in bulk by the Add Folder button.

3. Now you return to the Merge Documents dialog box, please (1) order these documents by Move Up and Move Down buttons; (2) specify a break between documents from the Break between documents drop down list; and then (3) click the Merge button. See screenshot:

Now all specified Word documents are combined into a new document as below screenshot shown:

Note: FYI, original formatting of all documents you merged is reserved in the merged result.