Two kinds of FGH4169 alloys with different carbon contents(0.022%、0.078%) were analysed by structure observation and image measurement or statistical calculation. The effect of carbon content on structures of FGH4169 alloy were investigated. The results showed that the average grain size of FGH4169 alloy with high carbon content decreased while the grain size had obvious differences. The type and morphology of carbides did not depend on carbon content.But the carbide size was affected strongly and the FGH4169 alloy with high carbon content formed PPB easily. In FGH4169 alloy with low carbon content, the increased number of strengthen phase, the large average size of strengthen phase grew and the reduce average gap of strengthen phase are beneficial to the improvement of strength.