The invention provides a low-temperature poly-silicon thin film transistor and a preparation method of the low-temperature poly-silicon thin film transistor. The LTPS TFT sequentially comprises a substrate, a heat conducting layer provided with a plurality of strip-shaped protrusions, a planarization layer and an active layer with a plurality of active channels, wherein the active layer is formed by carrying out the yellow laser process on a low-temperature poly-silicon thin film, a gate insulator, a gate electrode, an interlayer insulator, a source electrode and a drain electrode are arranged on the active layer, each strip-shaped protrusion is located outside one side of the position where the corresponding active channel is located, each strip-shaped protrusion and the corresponding active channel are adjacent to each other in position, and the length of each strip-shaped protrusion is larger than the width of the corresponding active channel. According to the low-temperature poly-silicon thin film transistor and the preparation method of the low-temperature poly-silicon thin film transistor, because large poly-silicon crystal grains can be obtained and the active channels of the thin film transistor can be completely located inside one single crystal grain, adverse impact of a poly-silicon crystal grain boundary on carrier mobility is avoided, the leakage current phenomenon caused by the crystal grain boundary is eliminated, and a simplest pixel circuit driving structure can be implemented.