Three kinds of YAG phosphor is chosen from a famous phosphor enterprise in China as research objects. The samples have same laser spectrum and central particle sizes (D50) are 9.3 μm, 13.6 μm and 16.7 μm respectively. At the condition of same filler-asphalt mass ratio and bonding volume, with the phosphor and 3014 type stand, white light LED lamp bead samples are produced. Optical parameters of the samples before and after aging are measured respectively by a spectrophotometer. Test results show that with the increasing of the center particle size of phosphor, color temperature approaches to the direction of high color temperature. When color temperature is constant, with the increasing of center particle size, luminous flux increases. Luminous decay reduces gradually with the increasing of phosphor particle size at the condition of one week accelerating aging time and 100 mA current.