In order to improve the security of the visible light communication system and further reduce the bit error rate of the system, chaotic sequences with pseudo-random characteristics, spread spectrum techniques, and pulse position modulation (PPM) are introduced into the light-emitting diode (LED) optical communication system. An LED optical communication system based on chaos pulse position modulation (CPPM) is realized. Under the additive white Gaussian noise(AWGN) channel, the influence of signal-to-noise ratio(SNR) on bit error rate of PPM system is analyzed. At the same time, the influence of the key, SNR and the length of chaotic sequence on the bit error rate of CPPM system are analyzed. Simulation results show that when the length of chaotic sequence is greater than 32, the CPPM system is superior to the PPM system, which can reduce the bit error rate of the system and improve the security of the system.