1. A mixed multi-spectrum light-sensing device, comprising at least two light-sensing pixel layers, wherein the light-sensing pixel layers each comprise a chemical coating light-sensing pixel layer and a semiconductor light-sensing layer, at least one chemical coating light-sensing pixel is arranged at the chemical coating light-sensing pixel layer and at least one semiconductor light-sensing pixel is arranged at the semiconductor light-sensing pixel layer; wherein the at least one chemical coating light-sensing pixel layer is arranged above the at least one semiconductor light-sensing pixel layer; or, wherein the at least one chemical coating light-sensing pixel layer is arranged below the at least one semiconductor light-sensing pixel layer; wherein two neighboring layers of the light-sensing pixel layers are each provided with a reading circuit; or two neighboring layers of the light-sensing pixel layers share a reading circuit, wherein the reading circuit is a reading circuit for an active pixel, a reading circuit for a passive pixel, or a mixed reading circuit for an active pixel and a passive pixel, wherein a sharing manner of the reading circuit comprises a single-layered or upper-and-lower-layer 4-point sharing manner, a single-layered or upper-and-lower-layer 6-point sharing manner, a single-layered or upper-and-lower-layer 8-point sharing manner, or a single-layered or upper-and-lower-layer any-number-of-point sharing manner; wherein the reading circuit comprises a first combining unit configured to perform pair-wise combining and sampling on proximate same-row different-column, different-row same-column, or different-row different-column pixels in a pixel array of each light-sensing pixel layer, to obtain sampling data of a first combining pixel; and a second combining unit configured to perform combining and sampling on the sampling data of the first combining pixel obtained by the first combining unit to obtain sampling data of a second combining pixel, wherein a pixel combining manner of the first combining unit or the second combining unit is a charge addition manner between same or different color pixels or a signal average manner between different color pixels, wherein the pixel combining manner between different color pixels conforms to a manner of color space conversion, so as to satisfy a color reconstruction requirement.