A novel fabrication technology of three-dimensional (3D) microstructures by 1064 nm Nd∶YAG laser irradiation is described. This technology employs an interesting phenomenon that a thermoplastic material melted by laser heating grows in liquid surrounding space. After switching off the laser irradiation, it immediately solidifies into a convex microstructure because of the heat release. The experimental setup of this fabrication technology has been developed, which utilizes a 1064nm Nd:YAG laser as light source, and an X-Y scanning stage to realize the relative movement between laser irradiation and thermoplastic material. Paraffin dots and lines have been manufactured with this experimental setup. The experimental results show, the width of paraffin dots is mostly determined by the size of focal spot, and their heights increase along with the extension of irradiation time or the enlargement of laser power. Initial research about the liquid temperature impacts on thermoplastic manufacturing results has been done.