This invention discloses a method for generating false random numbers including ciphering a first random number with a related ciphering method to get a ciphertext for XOR with the first random number to get the first XOR result to be XOR with a second random number in the second register to get a second result to be ciphered with a corresponding ciphering algorithm to get a ciphertext to be XOR with the second XOR result to get the false random number, which can generate fine random numbers with good ciphered code performance without external prompt input.