Abstract: Two kinds of weakly cohesive coals, low rank long flame coal and high rank lean coal were selected as the research objects, and they were mixed into coking coal and fat coal commonly used in coking plant. The process properties of coal samples mixed with different proportions (long flame coal mass fraction of 3%, 4%, 5%; lean coal mass fraction of 3%, 5%, 7%) were analyzed, and the thermal properties, micro strength and optical structure of crucible coke refined from coal blending samples were studied. The results show that the volatile content of long flame coal is high, when the mass fraction of long flame coal is less than 4%, the deterioration degree of coal adhesion index G, Audibert-Arnu dilatation b, total expansion (a+b) and the maximum thickness Y of colloidal layer are small, and the adhesion performance decreases slightly. When the mass fraction of long flame coal increases to 5%, the thermal properties of crucible coke deteriorate seriously, the PRI value of particle coke reactivity reaches the highest, and the PSR and MSI values of particle coke after reaction are the lowest. The volatile content of lean coal is low, when the mass fraction of lean coal is less than 7%, the process properties of coal samples and the thermal properties of crucible coke fluctuate in a certain range. The deterioration of OTI by long flame coal is mainly reflected in the increase of coke filaments, fragments and isotropy, and the deteriorationof OTI by lean coal is mainly reflected in the increase of fine-grained mosaic structure of coke.