A competition cheat-preventing system and method are applicable in a pigeon racing competition, wherein racing pigeons each wear a pigeon ring. An encrypted code-generating module is configured to generate contest encrypted codes from contest codes of the racing pigeons through specific parameter calculations. A barcode converting module is configured to convert the contest encrypted codes into two-dimensional barcodes. A barcode reading module is configured to read the two-dimensional barcodes to obtain original contest encrypted codes. An information transmission module is configured to transmit the original contest encrypted codes to a computer apparatus. An information-receiving module is configured to receive the original contest encrypted codes. A barcode decoding module is configured to perform reverse calculations to restore the original contest encrypted codes to original contest codes. A comparison module is configured to compare the original contest codes with contest codes recorded in the computer apparatus.