Magnetic nanoparticle supported ionic liquid catalysts were prepared.XRD,TEM and FT-IR were used for the characterization of the catalysts.The results show that ionic liquid was well supported on magnetic nanoparticles.Polyoxymethylene dimethyl ethers (PODE n ) was synthesized via the reaction catalyzed by the magnetic nanoparticle supported ionic liquid catalyst.The influences of catalyst dosage,the mole ratio of methanol to trioxane,reaction temperature and reaction time on catalytic activity were investigated.The optimum operating conditions were obtained:reaction temperature 110℃,reaction time 3 h,n (methanol)∶ n (trioxane)=2∶1,catalyst dosage 2.0%.Under these conditions,the conversion rate of trioxane was 99.8% and selectivity of PODE 3~8 reached 37.96%,catalyst still remained highly active even after being reused four times.