Halide perovskite (ABX3) materials have strong application potential in memristor materials due to their ion migration and charge trapping effects. Due to the low formation energy and weak binding strength between lead and iodine atoms in Cs0.05(FA0.85MA0.15)0.95PbI2.55Br0.4, iodine ions are easily lost from the perovskite lattice, resulting in defects and unsaturated lead atoms. Research on the field of solar cells has shown that by introducing triiodide ions, the defects in perovskite films can be significantly reduced and the film quality can be significantly improved. Therefore, different amounts of iodine are added to the perovskite precursor solution to introduce triiodide ions to explore its effect on the perovskite memristor being composed of Cs0.05(FA0.85MA0.15)0.95PbI2.55Br0.4. Experimental results show that by adding different amounts of iodine, the memristor curve has three obvious changes, such as the current in the I-V curve shows a gradually decreasing trend, the mutation performances of the memristor SET and RESET change significantly, the switch ratio varies greatly. The influence of the introduction of triiodide ion on the perovskite memristor is studied to adjust the current and switch ratio of the perovskite memristor, so as to be suitable for different application fields, and provide a direction for improving the performances of the perovskite memristor in the future.