The three-dimensional shape of a flower is integrated by morphogenesis along different independent floral axes. Differentiation along the floral proximodistal axis is tightly linked to specification of pollinators; however, it is still obscure how a flower patterns its proximodistal axis. The corolla of a Torenia fournieri flower exhibits strong differentiation along the proximodistal axis, including a distal petal lobe region, an intermediate corolla tube, and a proximal corolla neck region that is control by an ALOG (Arabidopsis LSH1 and Oryza G1) family homolog, TfALOG3. In this study, we report a floral specific BOP (BLADE-ON-PETIOLE) gene, TfBOP2, which is predominantly expressed in the proximal region of corolla. CRISPR knockout mutants of TfBOP2 have shorter proximal corolla tube and longer distal lobe region, with ectopic growth of conical cells in the fusion boundaries of corolla tube, consistent with its expression pattern as a proximal regulator. Mutants of BOP homologs in Arabidopsis thaliana also shows developmental defects in petal proximal region, favoring a conserved role of BOPs among different species. Genetic analysis demonstrates interaction between TfBOP2 and TfALOG3 in the control of corolla proximodistal patterning, since double mutants have shortest proximal corolla tube, while exhibiting normal boundary fusion. We further find that TfALOG3 physically interacts with TfBOP2, and can recruit TfBOP2 to the nucleus region, indicating their function possibly as a dimer. Our study unveils a plant universal BOP-ALOG complex being recruited to regulate flower proximodistal patterning of T. fournieri.