Respiratory diseases and pneumonia are among the most common diseases affecting more than 50% of the world's population. Various drugs have been developed to prevent and treat these diseases. rT1 peptide is a plant peptide isolated from the medicinal plant of Hibiscus sabdariffa. This 27-amino-acid peptide with inhibitory properties of human neutrophil elastase has been shown to have drug potential in the prevention and treatment of inflammatory lung diseases. Due to the high economic value of the compounds with neutrophil elastase inhibitory properties, in this study, for the first time, recombinant expression vector pBI121-rT1 was constructed with the aim of expressing rT1 peptide in plants. Because of the lack of rT1 gene sequence in databases, first, its appropriate gene sequence was designed and synthesized based on the Nicotiana tubaccum codon usage, the vectors used in this research, the structure and stability of its transcript and characteristics of the produced protein. For the designed sequence, the Codon Adaptation Index (CAI) and the GC frequency were 0.92 and 42.32%, respectively. In comparison to the main peptide, the stability of the designed peptide in human cells increased 25 times and its instability index calculated to be 20.90. Following amplification of the synthesized sequence by PCR reaction, it was cloned into pMCS5 vector. In order to express in plant-based systems, sub-cloning was performed in the expression vector pBI121 under the CaMV 35S promoter.