Submicron ZSM-5 was fast synthesized from coal series kaolin without organic templates with the assistance of crystal seeds. The crystallization conditions (seeds amount and SiO2/Al2O3 molar ratio), the crystallization processes and the mechanism were investigated. The results clearly indicated that the crystallization time could be shortened to 6 h by adding crystal seeds, and the crystal size was effectively reduced to submicron grade. Crystallization process demonstrated that hexa-coordinated Al of leached metakaolin was totally converted to tetra-coordinated Al, involved in the formation of ZSM-5 skeleton with Si species in the form of Si (1Al) and Si (2Al). The crystallization process of sub-micron ZSM-5 synthesized from coal series kaolin also abode by the solution-mediated transport mechanism. (C) 2017 Elsevier B. V. All rights reserved.