A data transmission and reception method and device are provided. The data transmission method includes: determining wavelength channels for data to be transmitted according to received wavelength channel information of an optical network unit (ONU); dividing the data to be transmitted in a sequence according to the number of the wavelength channels to obtain data packets; identifying the data packets according to the division sequence to obtain sequence identifiers of the data packets; and encapsulating the data packets into downstream frames of the wavelength channels in a one-to-one correspondence according to the sequence identifiers of the data packets, and transmitting the downstream frames of the wavelength channels separately to the ONU.