A method for inspecting surface defect of metal balls by image recognition includes the steps of feeding metal ball, capturing image for a first time, making metal ball rotate, capturing image for a second time, comparing images, and discharging metal balls. With the above steps, not only can the metal balls be sorted into the acceptable and the unacceptable metal balls, but the unacceptable metal balls can be sorted into different kinds according to the defects such as scratch, strain, and so on. Hence, effective data can be offered to improve the metal ball manufacturing process accurately.