The invention relates to a method for preparing an LED by means of quantum dot composite fluorescent particles. The composite fluorescent particles are utilized as fluorescent powder and mixed into a silica gel proportionally and coat a purple or blue light chip. After the silica gel is solidified, the purple or blue light chip is covered with a light extraction lens and filled with filling gel. The LED is obtained after the filling gel is solidified. The preparation process of quantum dot and inorganic fluorescent particle composite light-emitting materials is simple in technology and low in cost and energy consumption, the fluorescent light of the fluorescent powder is high, the exciting light wavelength range is wide, the emitting light wavelength range is long and narrow, and the fluorescent light stability is good. The composite fluorescent materials with quantum dots of different sizes or kinds are utilized as the fluorescent powder for manufacturing a multi-color light-emitting LED device, and the LED device is high in light-emitting efficiency, high in display index, wide in color gamut and good in fluorescent thermostability.