For the Er3+/Yb3+ codoped fluorophosphate glasses,Judd-Ofelt theory is used to analyse the influence of YbF3 as not a sensitizer but.an average component on the spectroscopic properties around 1530nm emission.The double roles of Yb3+,as a sensitizer and as an averagecomponent,are duscyssed.IT is found that Yb3+as an average component contributes to the increase of fluorescence lifetime,and Yb3+ as a sensitizer has the bestsensitization when its concentration is 2.4mol%.