If you say that someone has misjudged a person or situation, you mean that they have formed an incorrect idea or opinion about them, and often that they have made a wrong decision as a result of this.
双语例句
例： Perhaps I had misjudged him, and he was not so predictable after all.
也许我对他的判断是错误的，他根本就不是那么墨守成规。