Dreece Armstrong, of Brands Farm Way, Telford, took a knife from his kitchen and went to his ex's home.
She wasn't there, and he returned to his house from where he called the police.
He admitted charges of threats to kill and possessing an offensive weapon in a public place, and was handed a two year community order at Shrewsbury Crown Court on Thursday.
William Dudley, prosecuting, told the court that West Mercia Police received a call at 3.25pm on October 9 from the defendant, who was at his home address.
He told police that he wanted to stab and kill his ex girlfriend, and that he had "had enough of her."
Armstrong, 21, also said if police arrested him, when he was realised he would go and stab the girl.
Police were called to the address, where he twice more said that he wanted to kill her.
In interview he told officers the pair had got into an argument, and had split up just days earlier.
He said he became angry on the day in question, and had taken a kitchen knife and gone around to the home of his ex-girlfriend, with whom he has a child.
He admitted the charges at magistrates court, and the case was sent to the crown court for sentencing.
Danny Smith, defending, said his client had been polite and courteous during his time in custody, and had achieved some qualifications.
He said Armstrong was angry about a comment his ex-partner had made to his mother outside the school gates.
However, during his time in custody Armstrong had "got his head down", the court heard, and he will have work to go to on his release.
Judge Barrie said: "I come across you and I really don't understand what makes you tick in any shape or form."
He added the defendant had a "real problem," and it was not normal to take a knife out like he did.
He handed Armstrong a 24-month community order, which includes 40 rehabilitation days.
He was also ordered to pay a £250 fine, with £150 costs.