Emerging sodium-ion batteries (SIBs) have attracted a great attention as promising energy storage devices because of their low cost and resource abundance. Nevertheless, it is still a major challenge to develop anode materials with outstanding rate capability and excellent cycling performance. Compared to intercalation-type anode materials, conversion-type anode materials are very potential due to their high specific capacity and low cost. A new insight and summary on the recent research advances on nanostructured conversion-type anode materials for SIBs is provided herein. The corresponding synthesis methods, sodium storage properties, electrochemical mechanisms, advanced techniques on studying the crystal structures, and optimization strategies for high-performance batteries are presented. Finally, the remaining challenges and perspectives for the future development of conversion-type anode materials in the energy storage fields are proposed. Figure 17. a) Time-lapse images showing the evolution of morphology of a CuO NW at an applied voltage of −3 V during the first sodiation process. b,c) In situ TEM images showing the 1st sodiation and the 1st desodiation of the single SnO 2 nanowire, respectively. d) Time-resolved TEM images from video frames show morphology and structure evolution as a function of sodiation time and its electron diffraction (ED) patterns. Schematic and structural evolution of e,f) the V 2 O 3 ⊂C-NTs and g,h) V 2 O 3 ⊂C-NTs⊂rGO electrodes observed by in situ TEM experiments, respectively, during constant potential discharge at 5 V. i,k) The morphology evolution of two α-MoO 3 nanobelts during the first sodiation process in a low magnification, in which the red arrows denote the reaction front. j) The measured relationship between the sodiation front position and the sodiation time for above two α-MoO 3 nanobelts. l) Time-resolved TEM images from video frames show the sodiation process of an individual Co 9 S 8 -filled CNT with an open end. All scale bars are 200 nm. m) Time-resolved TEM images from video frames reveal the appearance of fractures during the electrochemical sodiation process of an individual Co 9 S 8 -filled CNT with closed ends. All scale bars are 100 nm. n) Schematic showing the setup of the in situ experiment. HAADF-STEM images showing o) pristine and p) sodiated FeF 2 NPs and q) cropped time-lapse frames throughout the sodiation process. a) Reproduced with permission. [131]