The invention relates to a pirfenidone derivative and a preparation method and use thereof and discloses a compound shown as in formula I or its pharmaceutically acceptable salt, crystal, hydrate or solvate, wherein R1 is selected from H or C1-C8 alkyl, R2, R3, R4, R5 and R6 are selected respectively or all from H or halogen, and at least one of the R2, R3, R4, R5 and R6 is halogen. The novel compound of the invention is significantly better than pirfenidone in anti-fibrosis activity and has an inhibitory rate of higher than 42% for fibroblast proliferation, as much as 5 times higher than 8.15% of pirfenidone, and the derivative has good industrial prospect.