Abstract: This paper focuses on the theme of “solar wind in the heliosphere and its interaction with the invading interstellar wind”, and discusses it from three aspects: current cognition, frontier problems, and exploration suggestions. The ions in the heliosphere include primary solar wind ions, pick-up ions converted partially from interstellar wind, and super-thermal ions. Among them, pick-up ions and super-thermal ions have their contribution from the local interstellar medium flow. The deep-space spacecraft have detected the prevalence of two modes in the heliosphere: the inner boundary of the heliosphere, the solar wind, the interplanetary turbulence, and the energy spectrum of the super-thermal ions. There are three types of cutting-edge issues: ① the territory never reached, that is, the tail of the heliosphere in the ecliptic plane and the outer heliosphere at high latitudes; ② the territory that has been reached, but some key variables have not been detected, such as the picked-up ions in the outer heliosphere; ③ the territory and variables that have been reached and detected, but the formation mechanism is unknown, such as the power-law spectrum and dual-mode of the super-thermal ions. To address these problems, we put forward the following suggestions: ① to design different flight paths and detect in different directions; ② to carry ion spectra instruments with wide energy band, covering the primary solar wind plasma, the pick-up ions, and the super-thermal ions; ③ to carry high sensitivity magnetometer to measure the compressible magnetic turbulence in the outer heliosphere.