Controllable synthesis of inorganic functional nano/microcrystals with desired phase/morphology is a focal theme in field of materials science. Herein, a green aqueous-based synthetic route has been developed to prepare uniform Ln(3+) (Ln = Eu, Yb/Er, Yb/Tm) doped YOF/Y6O5F8 microcrystals. The phase structure, particle morphologies, and photoluminescence properties were investigated by means of XRD, SEM, TEM, TG, and PL analysis. It is found that the as-synthesized YOF/Y6O5F8 microcrystals are uniform microdiscs with good dispersity and porous properties. The influences of the NH4HCO3/NaF feeding ratio on the phase structure, morphology, and size were investigated in detail. Moreover, the luminescence properties of the YOF:Ln(3+) and Y6O5F8:Ln(3+) are comparatively investigated via downconversion and upconversion processes from the lattice structure view. This synthetic strategy may provide a feasible and general case for green and controllable synthesis of other uniform inorganic nano/microcrystals.