The invention provides a data processing method and device and a computer readable storage medium, and belongs to the technical field of card reader communication. The method comprises the Steps: enabling a card reader to receive and analyze a data packet which is sent by a host and conforms to a first data structural formula, judging whether a first preset field in the data packet is the same as an address of the card reader or not, if yes, determining a data packet verification mode, and verifying the data packet according to the data packet verification mode; and if the verification is passed, determining whether the data packet contains security data, if so, processing the security data in the data packet according to the key to obtain plaintext data, determining a command type, executing corresponding operation according to the command type and the plaintext data, and returning a response data packet conforming to the first data structural formula to the host. According to the invention, the communication data can be effectively prevented from being monitored, stolen and tampered, so that the security of data transmission is ensured.