A pixel driving current extracting apparatus, comprising a plurality of driving current extracting circuits each corresponding to a pixel driving circuit for providing a pixel driving current to a pixel of a respective color, each of the driving current extracting circuits comprising: a driving current amplifying and converting unit connected to the corresponding pixel driving circuit for the pixel of the respective color, for amplifying and converting the driving current of the pixel driving circuit into a voltage signal; and a driving current computing unit connected to the driving current amplifying and converting unit, for computing a pixel driving current according to the voltage signal; characterized in that, an amplification ratio of the driving current amplifying and converting unit in the driving current extracting circuits corresponding to the pixel driving circuits for pixels of respective colors is inversely proportional to a magnitude of the pixel driving current of the pixels of the respective colors; the driving current amplifying and converting unit comprises a first amplifier and a first capacitor; a first input terminal of the first amplifier is connected to an end of the first capacitor and the pixel driving circuit corresponding to the driving current extracting circuit, and a second input terminal of the first amplifier is connected to a reference voltage (Vref); an output terminal of the first amplifier is connected to the other end of the first capacitor and the driving current computing unit; the amplification ratio of the first amplifier in the driving current extracting circuits corresponding to the pixel driving circuits for pixels of respective colors is inversely proportional to the magnitude of the pixel driving current of the pixels of the respective colors; the driving current computing unit is configured for performing operations of differentiating and amplifying the voltage signal to obtain the pixel driving current; the driving current computing unit comprises a second amplifier, a second switch, a third switch, a second capacitor and a third capacitor; the output terminal of the first amplifier is connected to an end of the second switch and an end of the third switch, respectively; the other end of the second switch is connected to an end of the second capacitor and a first input terminal of the second amplifier, respectively, and the other end of the second capacitor is grounded; and the other end of the third switch is connected to an end of the third capacitor and a second input terminal of the second amplifier, respectively, and the other end of the third capacitor is grounded. a driving current amplifying and converting unit connected to the corresponding pixel driving circuit for the pixel of the respective color, for amplifying and converting the driving current of the pixel driving circuit into a voltage signal; and a driving current computing unit connected to the driving current amplifying and converting unit, for computing a pixel driving current according to the voltage signal; characterized in that, an amplification ratio of the driving current amplifying and converting unit in the driving current extracting circuits corresponding to the pixel driving circuits for pixels of respective colors is inversely proportional to a magnitude of the pixel driving current of the pixels of the respective colors; the driving current amplifying and converting unit comprises a first amplifier and a first capacitor; a first input terminal of the first amplifier is connected to an end of the first capacitor and the pixel driving circuit corresponding to the driving current extracting circuit, and a second input terminal of the first amplifier is connected to a reference voltage (Vref); an output terminal of the first amplifier is connected to the other end of the first capacitor and the driving current computing unit; the amplification ratio of the first amplifier in the driving current extracting circuits corresponding to the pixel driving circuits for pixels of respective colors is inversely proportional to the magnitude of the pixel driving current of the pixels of the respective colors; the driving current computing unit is configured for performing operations of differentiating and amplifying the voltage signal to obtain the pixel driving current; the driving current computing unit comprises a second amplifier, a second switch, a third switch, a second capacitor and a third capacitor; the output terminal of the first amplifier is connected to an end of the second switch and an end of the third switch, respectively; the other end of the second switch is connected to an end of the second capacitor and a first input terminal of the second amplifier, respectively, and the other end of the second capacitor is grounded; and the other end of the third switch is connected to an end of the third capacitor and a second input terminal of the second amplifier, respectively, and the other end of the third capacitor is grounded.