The invention discloses a synthesis method of a small-
crystal-grain FER (
Ferrierite) 
molecular sieve with a laminar stacking structure. The synthesis method comprises the following steps: taking a 
silicon source, an aluminum source, alkali, an organic template agent and water as raw materials, and rotating and 
ageing at relatively low temperature to form initial gel; then carrying out dynamic 
crystallization to obtain a primary product; then removing the organic template agent under a mild condition by utilizing a lot of low-temperature plasmas generated through a 
dielectric barrier 
discharge(DBD) device, so as to obtain the small-
crystal-grain FER 
molecular sieve with the laminar stacking structure; finally, carrying out different depths of water 
stream coupled low-temperature 
plasma treatment on the prepared 
molecular sieve, so as to remove framework aluminum and adjust the acidic ratio of the FER molecular 
sieve, and further modify the shape and structure of the molecular 
sieve. The molecular 
sieve prepared by the invention not only has good stability, but also has a very strong 
carbon deposition resisting capability; when the molecular sieve is used for catalyzing n-
butene isomerization reaction, excellent performance is obtained, and the stability of a catalyst is effectively enhanced; the service life of the catalyst is extremely improved.