Divorced then remarried to non US citizen that does not nor qualify for SSN, I have three dependent children. Can I file head of household?

[SusanY1]

Probably.  If you are married to a nonresident alien you typically must either file as Married Filing Jointly (MFJ) or Married Filing Separately (MFS) unless you qualify to file Head of Household.  Since you have dependent children who can be your "qualifying relatives" for that purpose, you likely qualify.

Here is some more information about using the Head of Household filing status when your spouse is a nonresident alien Head of Household for Taxpayers with Nonresident Alien Spouse.