Duty‐cycled technology has been introduced as an efficient way to preserve node energy and prolong network lifetime for wireless sensor networks (WSNs). However, many applications with real‐time feature require that some message must be sent to the sink node within a limited time. The authors propose a novel data collecting scheme – MTDR which aims to minimise transmission delay in low‐duty‐cycle WSNs. In MTDR, all the nodes are assigned to the corresponding levels according to the hop count to the sink node, and calculate their minimum transmission delay to the sink node based on the shortest path structure. Finally, simulation results show that their proposed algorithm can achieve better performance compared with some related works.