Blue chip excitating YAG phosphor is one of the most commercial methods to realize the white LED.This method shows poor color rendering index because of lack of red band composition.The color rendering index of white LED is improved in this paper.Here,the MEH-PPV is mixed into YAG phosphors with the concentrations of 1 wt%,3 wt%,5 wt% and 10 wt%,respectively.We analyze the spectral changes at the current of 700 mA for the white LED.Under the impact of large current,we can obviously find the high thermal resistance from PN junction to the external environment because the cooling is not perfect.The high temperature will lead to rapid aging of LED chips and make MEH-PPV decompose and lose efficacy.The large current impact is yellow band before and after almost unchanged,which suggests that MEH-PPV can improve color rendering index,but its stability is far less than that of YAG phosphors.