The mathematical model of aviation cylindrical roller bearings fatigue life was established.The comparative analysis of the calculation methods for rolling bearing life was conducted for ISO281:1990(the equivalent of GB/T6391-2003)and ISO 281:2007(the equivalent of GB/T6391-2010),and the differences of the calculation method and the life modification factor were analyzed.Considering the lacking of aviation bearing samples and the difficulty of defining the value of modification factor,Dowson-Higginson equation was used to calculate the least EHD film thickness to determine the modification factor.The feasibility of this method was validated in the research of the life calculation of cylindrical roller bearing of some helicopter drive system.