Wang Yun was arrested last year after children at a kindergarten in Jiaozuo city were rushed to hospital after eating their morning porridge.
The court said she put sodium nitrite in the breakfast of her colleague's students for revenge after a fallout.
It described Ms. Wang as "despicable and vicious".
On Monday a local court in Jiaozuo sentenced Ms. Wang to death.
It said in a statement that she had put sodium nitrite into the porridge of the young students of another teacher in "revenge" after they had "argued over student management issues".
The court also said this was not the first time Ms. Wang had poisoned people, referencing an earlier incident where she bought nitrite online and poisoned her husband who suffered minor injuries.
One of the poisoned children died in hospital in January after spending 10 months in hospital.
The sentence is carried out by lethal injection or by firing squad." BBC