Ultra-reliable and low-latency communication (URLLC) is critical to enable real-time wireless control in tactile internet (TACNET). However, it requires significant wireless resource consumption due to the extreme quality-of-service (QoS) requirement. In this paper, we propose a dynamic QoS allocation method from the perspective of communication-control co-design. In the proposed method, the QoS of URLLC is adjusted in a control process, where high QoS is given to critical control periods while low QoS is given to non-critical ones. As a result, the proposed method can significantly reduce the wireless energy consumption compared with conventional method that uses high QoS during the whole control process. Simulation results show the performance of our method.