A light guide apparatus for enhancing light source utilization efficiency includes a light guide sheet, a light coupling structure and a light emerging structure. The light coupling structure is arranged on a surface of the light guide sheet and opposite to a light source. The light emerging structure is disposed on a surface of light guide sheet. Lights emitted by the light source enters into the light guide sheet via the light coupling structure and evenly emitted to outer environment via said light emerging structure, thereby enhancing light source utilization efficiency.