Receptor-like kinases play an indispensable role in plant growth and development, resistance to biotic and abiotic stresses, and are considered as important transmembrane signaling molecules in plants. Lectin-receptor like kinases (LecRLKs) belong to the second largest subfamily of receptor-like kinases, which have been rarely studied in plants. Our recent study showed that LecRK Ⅳ.3 plays an important role in plant response to salt stress and UV-B stress. Previous studies have shown that the kinase activity of the intracellular domain (ID) of receptor-like kinases is crucial for the function of LecRK Ⅳ.3. In order to elucidate whether LecRK Ⅳ.3 has kinase activity in vitro, LecRK Ⅳ.3ID was cloned and constructed into pET30a vector by one-step recombination method. The prokaryotic expression vector His-LecRK Ⅳ.3ID was obtained and transformed into 5 different Escherichia coli expression host strains. The optimal expression host of His-LecRK Ⅳ.3ID protein was explored based on the growth conditions of different host bacteria, and the optimal host for this protein was finally determined as OverExpress C43 (DE3). The fusion protein obtained from this host was mainly distributed in the supernatant. Western blot showed that the LecRK Ⅳ.3 protein could be recognized by Anti-His-HRP antibody.LecRK Ⅳ.3 exhibited kinase activity when detected by radioisotope method. The results not only lay a foundation for studying the biological function of LecRK Ⅳ.3, but also provide a theoretical reference for the purification of other protein kinases in the future.