The present invention relates to a distance adjustment system and a solar wafer inspection machine provided with the system. The inspection machine has a conveyer for carrying a solar wafer, an optical inspection system for inspecting the surface and color appearance of the wafer and an illumination inspection system. A holder is provided in the inspection position where the wafer is clamped along its width direction to prevent the wafer from offset. During the opto-electrical inspection, probes are brought into contact with conductive buses of the wafer and light is applied to the wafer to allow the probing of electric energy thus generated. An adjusting device is employed to adjust the clamping gap of the holder and the distance of the probes in accordance with the size of the solar wafer. The data are collected and transmitted to a sorting system for sorting the wafer.