Use Migration Assistant to copy some or all of your content from one Mac to another Mac.
Migration Assistant transfers documents, apps, user accounts, and settings from one Mac to another. It doesn’t delete information from your old Mac or replace the operating system (macOS) on your new Mac.
You can also use Migration Assistant to transfer from a Time Machine backup of your old Mac. Or transfer from a Windows PC.
Install the latest software updates available for each Mac. It’s not necessary for each Mac to be using the same version of macOS.
To transfer wirelessly, make sure that both computers have turned on and are near each other. If either Mac is using OS X El Capitan or earlier, also connect them to the same Wi-Fi network.
If antivirus, firewall, or VPN software is in use on either Mac, turn off that software until you're done.
Migration Assistant is included with your Mac—both as an app and as part of the setup assistant that opens when you first start up a new Mac.
Open Migration Assistant:
If your Mac starts up to a setup assistant, which asks for details like your country and network, skip to the next step, because migration is part of that setup.
If you already completed initial setup of your new Mac, open Migration Assistant. You can find it in the Utilities folder of your Applications folder. Or use Spotlight to find and open it. If asked for permission to make changes, enter your administrator password.
When asked how you want to transfer your information, select the option to transfer from a Mac, Time Machine, or startup disk. Click Continue.

Open Migration Assistant, then click Continue.
When asked how you want to transfer your information, select the option to transfer to another Mac. Click Continue.
When asked to select a Mac, Time Machine backup, or other startup disk, select the icon of the other Mac. Click Continue.
If you see a security code, make sure that it's the same code shown on your new Mac. Click Continue.
Migration Assistant calculates how much storage space is used by all of your information, including applications, user accounts, files, folders, and settings. Wait for the calculation to complete.
Select the checkbox next to each category of files that you want to transfer. Or click the next to a category and select specific items within it. Click Continue when done.

In the example pictured, Danny Rico and Olivia Rico are user accounts.
If transferring an administrator account, you’re asked to click Set Password and enter a secure password. Remember this password. You will need it to log in to the account on your new Mac.
If transferring a standard account, a temporary password is assigned and appears onscreen. Write down this password. When the user first logs in, they must enter this password, then enter their own new password when prompted.

If an account with the same name already exists on your new Mac, you’re asked to choose:
Replace the account on your new Mac with the account from your old Mac. You might also have the option to keep a copy of the replaced account’s data by moving it to the Deleted Users folder, where you can access that data later.
Or rename the old account before transferring it to your new Mac. This keeps both accounts, so that you can log in to them separately on your new Mac.

If asked for the password of an existing user who is already authorized on your new Mac, click Authorize, then enter that account's password.

Large transfers might need hours to complete, and might seem to pause occasionally. After Migration Assistant is done, quit Migration Assistant on both computers, then log in to the migrated account on your new Mac.
Migration Assistant transfers your email, but to access it you might first need to set up your email account again in your email app.
If you're not keeping your old Mac, learn what to do before you sell, give away, or trade in your old Mac. Those steps include the option to erase your old Mac and reset it to factory settings.