A light sensing method, applied to a light sensing system comprising a light sensor and at least one light source. The light sensor comprises a plurality of light sensing units. The light sensing method comprises: controlling the light sensor to capture images according to the light source； generating an exposure condition according brightness that each of the light sensing units senses, to control all the light sensing units to generate a target brightness distribution according to the exposure condition； and controlling the light sensing units to sense light from the light source according to the exposure condition. 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.
