The invention discloses a dyeing technology of polyester filament yarn cheese, comprising the following working procedures: loose type coning procedure, pretreatmenting procedure (one-step method with retreatment, boiling and bleaching), dyeing procedure, post-treatmenting procedure, dewatering and drying procedure; before the working procedure of loose coning procedure starts, polyester filament is steamed and shaped by supersaturated steam. The macromolecules of the polyester filament which is steamed and shaped by supersaturated steam finish structural rearrangement, thus the yarn cheese has stable size and does not shrink in the dyeing process so as to avoid the phenomenon of dyeing defects generated by the variation of dye liquor flow because of shrinkage in the dyeing process.