The visible light positioning system is the hot spot of current indoor positioning technology research. Aiming at the problem of inaccurate azimuth angle acquisition in single-lamp positioning system, this paper proposes a single Light Emitting Diode (LED) indoor positioning system based on marked LED. The scheme uses a single LED light with a non-flickering lamp bead as the transmitter to transmit information while realizing the lighting function. The smartphone acts as the receiver to capture images with bright and dark stripes, and obtain the azimuth angle by combining the geometric features of the projection and processing the algorithm. Then the position of the receiver is obtained by further calculation. The results show that in the actual application scenario, when the experimental heights are 1.75 and 1.45 m. The system can achieve average positioning errors of 6.9 and 6.5 cm, which verifies the feasibility and effectiveness of the scheme.