Luckily for me, I found this thread in my local board: https://bitcointalk.org/index.php?topic=2107937.0, this thread give a simple tutorial on how to find a private key of blockchain.info wallet address.
Firstly, I make a backup of blockchain.info wallet using wallet recovery phrase, then I write 12-16 "magic word" at notepad.
Two, I download this tools: https://github.com/iancoleman/bip39, then I went offline.
I run this tools in offline mode, I fill my 12-16 "magic word" to BIP39 Mnemonic form, and I get result privkey instantly.
Video mode: https://youtu.be/xwksiStDZD4 (with Indonesian subtitle)

After I have my private key, I follow this step https://bitcointalk.org/index.php?topic=990345.msg18991565#msg18991565

And yes, I can export the priv.key to electrum 3.0.6 too, and both of them have same result signature.

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EDIT: at step 5, remove "colour address" and fill it with priv.key
Its works for me and some user at my local sub

Big thanks for this thread, shorena.
I'll translate this thread in my local sub if you dont mind and give me permission for this
And I'll big mark Dos and Dont for warning, then put additon from JeremyB's and me.