Recently, borophene has attracted extensive interest as the wonder material, showing that line defects (LDs) occur widely at the interface between nu _{1/5} and nu _{1/6} boron sheets. Here, we study theoretically the electron transport through two-terminal disordered borophene nanoribbons (BNRs) with random distribution of LDs. Our results indicate that LDs strongly affect the electron transport properties of BNRs. Both nu _{1/5} and nu _{1/6} BNRs exhibit metallic behavior without any LD, in agreement with experiments. While in the presence of LDs, the overall electron transport ability is dramatically decreased, but some resonant peaks of conductance quantum are found in the transmission spectrum of any disordered BNR with arbitrary arrangement of LDs. These disordered BNRs exhibit metal-insulator transition with tunable transmission gap in the insulating regime. Furthermore, two evolution phenomena of resonant peaks are revealed for disordered BNRs with different widths. These results may help for understanding structure-property relationships and designing LD-based nanodevices.