The research studies a new LED portable desk lamp with V-groove cells light guide plate (LGP). Such LGP enables light of edge LED to be transmitted from the LGP with high efficiency and uniformity to enter a lighting area. Here, the so called V-groove cell is a unit composed of multiple V-grooves we provided, which may regulate light effectively with appropriate design to implement the design goal of lighting. We analyze the impact of V-grooves parameters on LGP, and further, use portable DL as an example to search for suitable V-groove units, and acquire successfully a set of LGP with high efficiency, high illuminance uniformity, and low direct glare. Compared to the commercially available DL, the efficiency is increased by 1.4 times, and the illuminance distribution of target area is similar. Obviously, such microstructure unit composed of multiple V-groove microstructure (VGM) cells can implement design goal of LED portable DL with high efficiency.