A wireless network device characterized by comprising: a memory (210, 908) configured to store routing latency information for routing from the wireless network device to other nodes in a network; a processor configured to determine transmission latency requirement of transmitting data packets from the wireless network device to a destination node according to transmission latency requirement information carried in the data packets and actual transmission time for data packets from a data source node to the wireless network device after obtaining the data packets to be transmitted and determining that the wireless network device is a node before a routing branch, query available routes from the wireless network device to the destination node, and the stored latency information corresponding to the available routes, select a route most approximate to the determined transmission latency requirement from the available routes according to a query result of the query module, and transmit the data packets, and update the latency information stored in the memory according to the actual latency of the present transmission of the data packet, after transmitting the data packet, wherein the memory (210, 908) is configured to transmit a predetermined amount of test packets to other nodes in the network for obtaining transmission latencies of the test packets in respective routes, calculate respectively transmission latency averages of the test packets in the respective routes and save the transmission latency averages as the routing latency information, and wherein the processor is configured to calculate difference values between the transmission latency requirement and the transmission latency averages in the respective available routes, and to select the available route with the minimal absolute difference value; and select the available route with the minimum transmission latency variance in case that the absolute difference values corresponding to multiple available routes are equal. a memory (210, 908) configured to store routing latency information for routing from the wireless network device to other nodes in a network; a processor configured to determine transmission latency requirement of transmitting data packets from the wireless network device to a destination node according to transmission latency requirement information carried in the data packets and actual transmission time for data packets from a data source node to the wireless network device after obtaining the data packets to be transmitted and determining that the wireless network device is a node before a routing branch, query available routes from the wireless network device to the destination node, and the stored latency information corresponding to the available routes, select a route most approximate to the determined transmission latency requirement from the available routes according to a query result of the query module, and transmit the data packets, and update the latency information stored in the memory according to the actual latency of the present transmission of the data packet, after transmitting the data packet, wherein the memory (210, 908) is configured to transmit a predetermined amount of test packets to other nodes in the network for obtaining transmission latencies of the test packets in respective routes, calculate respectively transmission latency averages of the test packets in the respective routes and save the transmission latency averages as the routing latency information, and wherein the processor is configured to calculate difference values between the transmission latency requirement and the transmission latency averages in the respective available routes, and to select the available route with the minimal absolute difference value; and select the available route with the minimum transmission latency variance in case that the absolute difference values corresponding to multiple available routes are equal.