A　seed-directed　approach　to　synthesizing　FeZSM-22　zeolite　without　organic　structure　directing　agent(OSDA)was　developed　by　using　Fe-rich　diatomite　as　all　aluminum　and　iron　sources.The　FeZSM-22　zeolite　with　optimal　crystallinity　and　purity　can　be　obtained　by　systematically　adjusting　feed　composi-tion　and　synthesis　conditions.Characterizations　show　that　FeZSM-22　zeolite　synthesized　with　OSDA-free　owns　high　crystallinity,obvious　thin　needle-shaped　morphology　and　high　Bronsted/Lewis　acid　ratio.Significantly,when　used　for　n-octane　hydroisomerization　reaction,its　derived　catalyst　exhibits　the　best　catalytic　performance　reflected　by　the　highest　selectivity　to　C8　isomers　compared　to　the　two　reference　catalysts　prepared　based　on　a　Fe-containing　and　a　Fe-free　ZSM-22　synthesized　through　an　OSDA-directed　route　from　natural　diatomite　and　conventional　chemicals,respectively.This　work　provides　an　alternative　route　to　sustainably　synthesizing　heteroatomic　zeolites　with　high　performance.