An 81-year-old woman was robbed at knife-point in her home Sunday by a creep who said he’d kill her if she cried, cops said.

The woman told cops the teenager knocked on her door in Coney Island about 3 p.m. and claimed to be with Con Edison. When she cracked the door, he pushed his way inside.

“Cry and I’ll kill you,” he threatened while holding a knife to her throat, cops said.

The robber taped the woman’s mouth shut. He also stole the watch from her wrist. Somehow, she escaped after about an hour and called 911 from her building’s security desk.

“He pushed me,” the woman said. “He took knife. It was terrible, terrible. I had to go to hospital.”

The thief put her watch back in a drawer but took off with several other items, including a Sony digital camera, an electronic picture frame, two Apple iPods, a gold medallion and $18, cops said.