A method for reliable fatigue life analysis and assessment based on Birnbaum-Saunders(B-S) distribution was studied

and life scatter factor formulas of B-S distribution based on median value and mean value was derived respectively. Then

for some special cases of test data

life scatter factor formulas of B-S distribution based on the maximum and minimum order statistics was established. Formulas show that

the median and mean life scatter factors are decreased with the increasing of the scale parameter of B-S distribution

and the maximum and the minimum life scatter factors are constant. Case calculation results show that life scatter factors of B-S distribution are usually less than that of the lognormal distribution's.