A wire bonding method includes the following steps. First, a substrate including at least one metal finger is provided. Next, a first chip including at least one first boding pad is disposed on the substrate. Next, a metal ball bump is foamed on the corresponding metal finger. Next, a first wire is formed from the metal ball bump toward the corresponding first boding pad. Next, a first free air ball is formed on the first wire by electronic flame-off process. Then, the first free air ball connected to the first wire is pressed on the corresponding first boding pad, such that the first wire is located between the first free air ball and the corresponding first boding pad.