Hi, thanks for your inform but I a little bit confused. can I save my all BTC in electrumwallet in this method. I dont want to loss it.
Yes, your seed will restore your old Electrum wallet.. with all the addresses and transactions etc. To test, in Electrum goto: "File -> New\Restore -> Standard Wallet -> I already have a seed", then enter your seed and click next... add a password if you want (DOES NOT have to be the same as your old one)
It should recreate your old wallet with the same addresses and transactions.
In Electrum passwords are only used for encrypting the private keys in the wallet file and encrypting the wallet file as a whole... they don't impact on the seed at all. They are NOT BIP39 Passphrases. Note that you don't even need to remove your old wallet first, you can just create a new wallet file (different name to old wallet) and restore your seed... so you can test it to make sure you know how to make it work
