A light sensing method applied to a light sensing system comprising a first light sensor and at least one light source. The first light sensor comprises a plurality of light sensing units. The light sensing method comprises: (a) respectively controlling an exposure condition according to distances between each of the sensing unit and the light source； and (b) controlling the light sensing units to sense light emitted from the light source according to the exposure time or the exposure frequency. The light sensing system can have a better SNR via adjusting the exposure condition for each one of the light sensing units. Such light sensing method can be applied to compute physiological parameters.一種光感測方法，其運用在一光感測系統上，光感測系統包含一第一光感測器以及至少一光源，且第一光感測器包含複數個光感測單元。此光感測方法包含：(a) 根據每一個光感測單元與光源的距離，分別控制光感測單元的曝光條件；以及(b) 根據曝光條件來使光感測單元感測光源發出的光。藉由各別調整每一個光感測單元的曝光條件，可使得光感測系統具有較佳的訊號雜訊比。此光感測方法可運用在測量生理參數上。
