Understanding the formation of latent track by energetic heavy ions is important for the fields of nuclear waste disposal, nuclear fuel and modification of materials.However, the details of the mechanism for the track formation in non-amorphizable materials are still being debated. Here, we report on the fine structure formation of latent tracks, which changes from cylinder to sandglass as a function of the ion-penetrating length, in a typical non-amorphizable material, rutile TiO 2 . Based on inelastic thermal spike model, we show that the outflow of molten phase produces the hillocks on surface and the void-rich zone near surface, while at a deep depth, the lack of outflow and the rapid recrystallization result in the absence of tracks. Moreover, the morphology of tracks depends on the velocity of molten phase outflow and recrystallization. Our perspective provides a new interpretation in the radiation damage for both amorphizable and non-amorphizable materials.