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WirelessHART is a wireless sensor network that is widely used in real-time demand analyses. A key challenge faced by WirelessHART is to ensure the character of real-time data transmission in the network. Identifying a priority assignment strategy that reduces the delay in flow transmission is crucial in ensuring real-time network performance and the schedulability of real-time network flows. We study the priority assignment of real-time flows in WirelessHART on the basis of the multi-channel time division multiple access (TDMA) protocol to reduce the delay and improve the ratio of scheduled. We provide three kinds of methods: (1) worst fit, (2) best fit, and (3) first fit and choose the most suitable one, namely the worst-fit method for allocating flows to each channel. More importantly, we propose two heuristic algorithms&#8212;a priority assignment algorithm based on the greedy strategy for <i>C</i> (WF-C) and a priority assignment algorithm based on the greedy strategy for <i>U</i>(WF-U)&#8212;for assigning priorities to the flows in each channel, whose time complexity is <inline-formula> <math display="inline"> <semantics> <mrow> <mi>O</mi> <mo stretchy="false">(</mo> <mi>m</mi> <mi>a</mi> <mi>x</mi> <mrow> <mo stretchy="false">(</mo> <mi>N</mi> <mo>&lowast;</mo> <mi>m</mi> <mo>&lowast;</mo> <mi>l</mi> <mi>o</mi> <mi>g</mi> <mrow> <mo stretchy="false">(</mo> <mi>m</mi> <mo stretchy="false">)</mo> </mrow> <mo>,</mo> <msup> <mrow> <mo stretchy="false">(</mo> <mi>N</mi> <mo>&#8722;</mo> <mi>m</mi> <mo stretchy="false">)</mo> </mrow> <mn>2</mn> </msup> <mo stretchy="false">)</mo> </mrow> <mo stretchy="false">)</mo> </mrow> </semantics> </math> </inline-formula>. We then build a new simulation model to simulate the transmission of real-time flows in WirelessHART. Finally, we compare our two algorithms with WF-D and HLS algorithms in terms of the average value of the total end-to-end delay of flow sets, the ratio of schedulable flow sets, and the calculation time of the schedulability analysis. The optimal algorithm WF-C reduces the delay by up to <inline-formula> <math display="inline"> <semantics> <mrow> <mn>44.18</mn> <mo>%</mo> </mrow> </semantics> </math> </inline-formula> and increases the schedulability ratio by up to <inline-formula> <math display="inline"> <semantics> <mrow> <mn>70.7</mn> <mo>%</mo> </mrow> </semantics> </math> </inline-formula>, and it reduces the calculation time compared with the HLS algorithm.