So far as I can tell, Bitcoin core (as of v23.0) has no obvious facility to import a master private key and use that key as the basis of a hierarchical deterministic (HD) wallet.

It has a facility for importing ordinary private keys of the sort that were generated before implementation of HD key derivation, but I doubt that would do anything useful with a master private key.

As we all know, what Bitcoin Core's developers intended us to do is to use the "Backup Wallet" option in the "File" menu and put copies of that in safe places *on other devices*. Then restore from one of those backups if the active wallet is damaged or lost.

In the "File" menu under "Create Wallet" there is a checkbox option to "Make Blank Wallet" whose tooltip says 
> "Blank wallets do not initially have private keys  or scripts. Private keys and addresses can be imported, or an HD seed can be set, at a later time". 

However I believe you don't have the HD seed, only a master private key derived from such a seed (as I understand it from [BIP32](https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki)).



I suspect that in principle, it is theoretically possible to construct from a master private key, an empty wallet.dat file of the sort that Bitcoin core might create when first run and before it has started an initial blockchain download (IBD) or built any indexes or UTXO sets etc. Then that reconstructed wallet.dat file ought to be usable with Bitcoin core. However I do not know of any tool to do this.

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Related: 

- https://bitcoin.stackexchange.com/q/68039/13866
- [Developer reference for `sethdseed`](https://developer.bitcoin.org/reference/rpc/sethdseed.html)
- [BIP32](https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki)
  > [![BIP32 key derivation diagram][1]][1]


  [1]: https://i.sstatic.net/OHhq1.png