Hello @Felix Wu
Thank you for reaching out, and a warm welcome to the Docusign Community! Your presence here is greatly valued, and we're all about sharing knowledge and supporting each other.
We understand you uploaded an Excel file for signature and are seeking to download it in its original Excel format once completed. Great question!
While Docusign supports the upload of Excel files ( Article: Supported File Formats ), all documents are converted to PDF upon upload for the esignature process. Consequently, it is not possible to retain the original Excel file format for the output. The signed document downloaded from Docusign will always be in PDF format.
We sincerely apologize. We understand this might be a limitation for your needs, and we encourage you to consider submitting this as a product suggestion on our Ideas board: Submit a feature request. That’s where ideas from Docusign users like you can submit ideas to improve Docusign’s features, and where you can also vote on ideas from other members.
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Let us know if you need further assistance. Here if you need us!
Sincerely,
Melanie | Docusign Community Moderator
If this helped, feel free to click "Best Answer"
Thanks for your kindly reply.
Hello @Felix Wu,
You're welcome! If the suggested solution was helpful, please consider marking it as "Best Answer ✅". This helps other community members with similar questions find the solution more easily. 
Let us know if you still need further assistance. Have a great day!
Sincerely,
Melanie| Docusign Community Moderator
Helpful? Feel free to hit “Best Answer” so others can benefit too!