Abstract: Based on comprehensive screening, lattice parameters including fuel composition, moderator material, lattice size and structure are redesigned for thorium molten salt reactor (TMSR) applying SONG/TANG-MSR codes. Innovatively, a fuel composition without BeF2 is adopted to increase the solubility for actinides (ThF4, UF4), and BeO is introduced as moderator to improve neutron economy. Moreover, SiC cladding is employed to separate fuel and moderator. Meanwhile such ceramic cladding contributes to maintain structure stability and improve resistance to radiation. With these lattice parameters, TMSR can achieve a high breeding ratio and maintain a negative power coefficient as well. Based on this lattice design, TMSR can have excellent performance of safety and sustainability.