Gauss fitting function is used to determine the Gauss-like radiation pattern of LED with small divergence angle, and the line-of-sight channel model of LED is established according to the optical radiation characteristics and radiation pattern. The relationship between the received optical power and the channel parameters of various multi-band LEDs obeying the Lambertian and Gauss-like modes is actually measured. The experimental results show that the average relative error between the measured value of received optical power and the theoretical value of channel DC gain calculation is less than ±6%, which verifies the versatility and correctness of the line-of-sight channel model proposed in this paper.