A data transmission method, applied to a network access device, comprising: determining a size of a transmission block which can be sent on an available time-domain resource of a time slot to be scheduled, when a first length of a time-domain resource required by a transmission block to be transmitted is greater than a second length of the available time-domain resource of the time slot (101; 204); dividing the transmission block to be transmitted into a first transmission sub-block and a second transmission sub-block based on the size of the transmission block, wherein a third length of a time-domain resource required by the second transmission sub-block is equal to a difference between the first length and the second length (102; 205); determining the first time-domain resource for sending the second transmission sub-block in a next time slot after the time slot based on the third length of the time-domain resource required by the second transmission sub-block (103; 206); sending a first resource allocation message to a terminal, wherein the first resource allocation message comprises the size of the first transmission sub-block, first indication information representing the available time-domain resource of the time slot configured to send the first transmission sub-block, and second indication information of the first time-domain resource configured to send the second transmission sub-block in the next time slot (104; 207); and sending the first transmission sub-block on the available time-domain resource of the time slot, and the second transmission sub-block on the first time-domain resource of the next time slot; wherein before sending the first resource allocation message to the terminal, the method further comprises: determining a first indicator value and determination information indicating whether a number of a first start symbol is greater than a preset value, according to the second length and the number of the first start symbol of the available time-domain resource of the time slot; determining a second indicator value according to the third length and the number of a second start symbol of the first time-domain resource configured to transmit the second sub- transmission block in the next time slot; wherein the first indication information comprises the first indicator value and the determination information, and the second indication information comprises the second indicator value. determining a size of a transmission block which can be sent on an available time-domain resource of a time slot to be scheduled, when a first length of a time-domain resource required by a transmission block to be transmitted is greater than a second length of the available time-domain resource of the time slot (101; 204); dividing the transmission block to be transmitted into a first transmission sub-block and a second transmission sub-block based on the size of the transmission block, wherein a third length of a time-domain resource required by the second transmission sub-block is equal to a difference between the first length and the second length (102; 205); determining the first time-domain resource for sending the second transmission sub-block in a next time slot after the time slot based on the third length of the time-domain resource required by the second transmission sub-block (103; 206); sending a first resource allocation message to a terminal, wherein the first resource allocation message comprises the size of the first transmission sub-block, first indication information representing the available time-domain resource of the time slot configured to send the first transmission sub-block, and second indication information of the first time-domain resource configured to send the second transmission sub-block in the next time slot (104; 207); and sending the first transmission sub-block on the available time-domain resource of the time slot, and the second transmission sub-block on the first time-domain resource of the next time slot; wherein before sending the first resource allocation message to the terminal, the method further comprises: determining a first indicator value and determination information indicating whether a number of a first start symbol is greater than a preset value, according to the second length and the number of the first start symbol of the available time-domain resource of the time slot; determining a second indicator value according to the third length and the number of a second start symbol of the first time-domain resource configured to transmit the second sub- transmission block in the next time slot; wherein the first indication information comprises the first indicator value and the determination information, and the second indication information comprises the second indicator value. determining a first indicator value and determination information indicating whether a number of a first start symbol is greater than a preset value, according to the second length and the number of the first start symbol of the available time-domain resource of the time slot; determining a second indicator value according to the third length and the number of a second start symbol of the first time-domain resource configured to transmit the second sub- transmission block in the next time slot; wherein the first indication information comprises the first indicator value and the determination information, and the second indication information comprises the second indicator value.