The present disclosure relates to a data communication method and system. The method includes: a first terminal continuously generating a communication carrier signal; sending by the first terminal a communication data signal carrying a data packet to be processed, beginning to record the first number of pulses when the first terminal completes sending the data packet to be processed; receiving by the second terminal the communication data signal, beginning to record the second number of pulses when the second terminal completes receiving the data packet to be processed, generating a response data packet sending, by the second terminal, the response data packet to the first terminal when detecting that the second number reaches a pulse number threshold N; and allowing, by the first terminal, to begin receiving the response data packet when detecting that the first number is within a threshold range.