1. A decoding method for low density parity check, adapted to an electronic device, and the decoding method comprising: receiving a message and executing an iteration decoding of the low density parity check to the message; obtaining a plurality of first belief values of the message in an (i−1) th iteration of the iteration decoding, wherein i is a positive integer greater than 1; obtaining a first energy summation of the first belief values; obtaining a plurality of second belief values of the message in an i th iteration of the iteration decoding; obtaining a second energy summation of the second belief values; determining whether the second energy summation is smaller than the first energy summation and whether a difference between the second energy summation and the first energy summation is greater than a first threshold; and generating a decoding result of the message according to the first belief values when the second energy summation is smaller than the first energy summation and the difference between the second energy summation and the first energy summation is greater than the first threshold.