Mark Ballas SLAMS 'Dance Moms' -- That Woman is a Tyrant

"Dancing with the Stars" pro Mark Ballas has a MAJOR problem with the "Dance Moms" reality show -- telling TMZ, the angry screaming dance coach is verbally abusing the kids ... and she doesn't know jack squat about dancing.

In case you haven't seen the show ... dance company owner Abby Lee Miller has become famous for berating the children ... once telling a crying little girl, "You save those tears for your pillow, in your room, alone."

Mark tells us, "She's not dancing, she's just yelling at them" ... adding, "I just don't think it's the correct way to teach somebody ... Those kids are 6 years old. They're learning. They're babies ... They need to be treated the correct way."