The precision hot embossing of microlens array needs heat preservation time, leading to poor efficiency. Hence, a rapid hot embossing of micro-arch array on polymer light guide plate (LGP) is proposed using a heated microgrooved die core. It only performs a thermal deformation for micro-scale surface layer flowing inside microgroove spaces without changing macro workpiece sizes. The objective is to develop the hot embossing process of microlens array of micro-optics with high machining efficiency and low energy-consumption. First, the micro-optics performances of LGP are analyzed with regard to the shape and size of micro-arch array; then the micro-grinding is employed to machine precision and smooth microgroove array on steel die core; finally, the rapid and accurate forming process of micro-arch array and its micro-optics application are studied. The micro-optics analyses show that the height and distribution density of micro-arch array greatly influence the micro-optics performance. The hot embossing experiments show that by using a microgroove array die core with an average groove depth of 104 μm and an average groove angle of 121°, the 50-μm-height 3D micro-arch array may be precisely formed in 3 s in the case of 12 MPa in loading pressure and 110 ℃ in loading temperature. Compared with the general screen-printing 2D micro-dot array with 8.2-μm-height, the LGP patterned with micro-arch array increases the LGP irradiance intensity by 21% and its uniformity by 27%, respectively. It contributes to the micro-optics precision design and fabrication applied for LED lighting industry.