[Objective] The research aimed to reveal the functions of NAC and UBA domains in Peatl's thermal stability. [Method] Fusion expression vectors of Pearl protein and the 3 deletion mutants were constructed. The recombinant plasmids were induced by IPTG and the target proteins (Peatl, Peatl-△CD99,Peatl-△ND49 and Pearl-△ND108 )were expressed obtained by AKTA and its thermal stability was analyzed. [Result] The research found that 3 deletion mutants have good thermal stability like Pearl. [Conclusion] The research demonstrated that the coexistence of NAC or UBA domains is not necessary to thermal stability of Pearl protein , and they may give the protein particular stability structure seperately.