The invention discloses an ion rectification research method of a tapered nanopore with a pH-adjustable electrolyte layer. On the basis of a structural characteristic of the tapered nanopore, the simulated size and boundary condition of the nanopore are set; initial conditions of the laminar flow, sparse material transferring, and static electric field in the nanopore are set; and the surface-ion-penetrable electrolyte layer thickness of the nanopore is set and the electric charge density in the electrolyte layer changes with the pH change. The improved stokes-brinkman equation and multi-ion PNP equation for ion transporting are used. Four kinds of ions in a solution is studied comprehensively, wherein four kinds of ions include two kinds of ions separated from background salt and H+ and OH- that decide pH values. Rectification characteristics of the tapered nanopore with the pH-adjustable electrolyte layer under different pHs and with different solution concentration values can be simulated.