A processor-implemented method for lightening at least one layer of a neural network with a plurality of layers comprising plural nodes and having weighted connections between neighboring nodes in neighboring layers, wherein the method comprises the steps of: performing a truncation operation and a cutoff operation to obtain a lightweight range of lightened weighted connections, the truncation operation comprising setting values of weighted connections less than a first positive non-zero value and greater than a first negative non-zero value to zero, and the cutoff operation comprising setting values of weighted connections greater than a second positive non-zero value and less than a second negative non-zero value to said second positive non-zero value and said second negative non-zero value, respectively, and wherein lightened weighted connections, corresponding to weighted connections having a value between the first positive non-zero value and the second positive non-zero value or a value between the second negative non-zero value and the first negative non-zero value, have maintained values corresponding to the value of corresponding weighted connections; shifting a distribution range of the lightweight range of lightened weighted connections toward zero based on the first positive non-zero value and the first negative non-zero value; and determining a minimum number of bits for representation of elements in a finite set corresponding to the lightweight range, and representing the lightened weighted connections based on the determined minimum number of bits, thereby reducing a bit size for each lightened weighted connection, wherein the first positive non-zero value, the second positive non-zero value, the first negative non-zero value and/or the second negative non-zero value are determined by iteratively adjusting said first positive non-zero value, second positive non-zero value, first negative non-zero value and/or second negative non-zero value until a performance index of the neural network having the lightened weighted connections meets a preset criterion. wherein the method comprises the steps of: performing a truncation operation and a cutoff operation to obtain a lightweight range of lightened weighted connections, the truncation operation comprising setting values of weighted connections less than a first positive non-zero value and greater than a first negative non-zero value to zero, and the cutoff operation comprising setting values of weighted connections greater than a second positive non-zero value and less than a second negative non-zero value to said second positive non-zero value and said second negative non-zero value, respectively, and wherein lightened weighted connections, corresponding to weighted connections having a value between the first positive non-zero value and the second positive non-zero value or a value between the second negative non-zero value and the first negative non-zero value, have maintained values corresponding to the value of corresponding weighted connections; shifting a distribution range of the lightweight range of lightened weighted connections toward zero based on the first positive non-zero value and the first negative non-zero value; and determining a minimum number of bits for representation of elements in a finite set corresponding to the lightweight range, and representing the lightened weighted connections based on the determined minimum number of bits, thereby reducing a bit size for each lightened weighted connection, performing a truncation operation and a cutoff operation to obtain a lightweight range of lightened weighted connections, the truncation operation comprising setting values of weighted connections less than a first positive non-zero value and greater than a first negative non-zero value to zero, and the cutoff operation comprising setting values of weighted connections greater than a second positive non-zero value and less than a second negative non-zero value to said second positive non-zero value and said second negative non-zero value, respectively, and wherein lightened weighted connections, corresponding to weighted connections having a value between the first positive non-zero value and the second positive non-zero value or a value between the second negative non-zero value and the first negative non-zero value, have maintained values corresponding to the value of corresponding weighted connections; shifting a distribution range of the lightweight range of lightened weighted connections toward zero based on the first positive non-zero value and the first negative non-zero value; and determining a minimum number of bits for representation of elements in a finite set corresponding to the lightweight range, and representing the lightened weighted connections based on the determined minimum number of bits, thereby reducing a bit size for each lightened weighted connection, wherein the first positive non-zero value, the second positive non-zero value, the first negative non-zero value and/or the second negative non-zero value are determined by iteratively adjusting said first positive non-zero value, second positive non-zero value, first negative non-zero value and/or second negative non-zero value until a performance index of the neural network having the lightened weighted connections meets a preset criterion.