A wafer pre-alignment device, comprising: a first unit configured to drive a wafer to rotate or move upward or downward, the first unit comprising a first chuck for retaining the wafer; a second unit configured to drive the wafer to translate relative to the first chuck; a position detector comprising an image sensor disposed above the first chuck, and a lens disposed under the first chuck, wherein the position detector is configured to provide information indicating a position of the wafer relative to the first chuck on to the image sensor, wherein the first unit and the second unit are configured to adjust the position of the wafer relative to the first chuck based on the information obtained by the image sensor, characterized in that: the position detector comprises a reflective optical system and a catadioptric optical system, wherein the reflective optical system comprises a first light source for producing a light beam having a first wavelength, a first lens assembly, the image sensor and the lens, the lens reflecting the light beam having the first wavelength, the first lens assembly disposed above the first chuck and under the image sensor and configured to direct the light beam having the first wavelength through the wafer and on the lens and the light beam having the first wavelength is then reflected onto the image sensor; the catadioptiric optical system comprises a second light source for producing a light beam having a second wavelength, a second lens assembly, the image sensor and the lens, the lens allowing the transmission of the light beam having the second wavelength, the second lens assembly disposed under the first chuck and configured to cause the light beam having the second wavelength to transmit through the wafer and the lens and then reach the image sensor. a first unit configured to drive a wafer to rotate or move upward or downward, the first unit comprising a first chuck for retaining the wafer; a second unit configured to drive the wafer to translate relative to the first chuck; a position detector comprising an image sensor disposed above the first chuck, and a lens disposed under the first chuck, wherein the position detector is configured to provide information indicating a position of the wafer relative to the first chuck on to the image sensor, wherein the first unit and the second unit are configured to adjust the position of the wafer relative to the first chuck based on the information obtained by the image sensor, characterized in that: the position detector comprises a reflective optical system and a catadioptric optical system, wherein the reflective optical system comprises a first light source for producing a light beam having a first wavelength, a first lens assembly, the image sensor and the lens, the lens reflecting the light beam having the first wavelength, the first lens assembly disposed above the first chuck and under the image sensor and configured to direct the light beam having the first wavelength through the wafer and on the lens and the light beam having the first wavelength is then reflected onto the image sensor; the catadioptiric optical system comprises a second light source for producing a light beam having a second wavelength, a second lens assembly, the image sensor and the lens, the lens allowing the transmission of the light beam having the second wavelength, the second lens assembly disposed under the first chuck and configured to cause the light beam having the second wavelength to transmit through the wafer and the lens and then reach the image sensor. the position detector comprises a reflective optical system and a catadioptric optical system, wherein the reflective optical system comprises a first light source for producing a light beam having a first wavelength, a first lens assembly, the image sensor and the lens, the lens reflecting the light beam having the first wavelength, the first lens assembly disposed above the first chuck and under the image sensor and configured to direct the light beam having the first wavelength through the wafer and on the lens and the light beam having the first wavelength is then reflected onto the image sensor; the catadioptiric optical system comprises a second light source for producing a light beam having a second wavelength, a second lens assembly, the image sensor and the lens, the lens allowing the transmission of the light beam having the second wavelength, the second lens assembly disposed under the first chuck and configured to cause the light beam having the second wavelength to transmit through the wafer and the lens and then reach the image sensor.