The present application relates to detection technology, it provides a detection method and detection system of blood oxygen saturation, this method includes: controlling two parallel light emitting diodes to emit a red light and an infrared light periodically to a finger detecting the red light and infrared light passing through the finger and converting them into a red light electrical signal and an infrared light electrical signal respectively separating pulsating components from the two electrical signals to obtain a separated variation of red light in one cycle and a separated variation of infrared light in one cycle calculating the blood oxygen saturation based on the variations of red light and infrared light amplifying and filtering the blood oxygen saturation prior to converting the blood oxygen saturation into digital signal by analog-to-digital converter.
