Abstract: The structure of fee data automatically collecting system in public utility is introduced. With the study of the security of the system, a synthetic security scheme is put forth, which is using random number to decide the sequences of the data to be transmitted, inserting random numbers with no use to improve information redundance, using monodirectional hash function to get the exclusive value of the transmitted data and adopting the one time encrypt to encipher the hash value and the random number. This method is simple and highly efficient.