The modified iron catalysts for direct synthesis of light olefins from syngas were investigated. A series of catalysts were prepared by co-precipitation method and characterized by SEM, BET and X-ray diffraction methods. Catalytic performance of the catalysts was tested in a fixed-bed reactor. The experimental results showed that Zn-modified iron catalyst displayed a high selectivity for light olefins and one through CO conversion. Alkali metal modified catalytic performances as electronic promoter that promoted the formation of light olefins. Meanwhile, the combination of Na + and Zn is a key factor to optimize the light olefins selectivity of catalyst in syngas to light olefins. The modified iron catalyst (Fe/Zn molar ratio = 1, prepared by co-precipitation using Na2CO3 as precipitant) displayed a CO conversion of 95.09%, a light olefins selectivity of 53.32%, and an olefin/paraffin ratio up to 6.91. That catalyst has high stability and activity in the performance test time on stream of 100 h.