Abstract: A method for crack initiation life prediction of components is presented. This method employs the life of a given component obtained from endurance tests under spectrum load to predict the life of another untested same type component by analogy.The formula for analogy life prediction is deduced from Miner's theory and formula SmN=C as follows:or where ni,, Sai, Δgi and λ are load cyclic number, stress amplitude, overload increment and life cyclic number of the given component in i level; ni', S'ai, Δgi' and λ' are those of the unknown component; Sap and Δgp are any constant stress amplitude and overload increment （they may be taken as unit in calculation）; m1, m'i are constant （generally between 5 and 10） and may be estimated from the S-N curve or by experiments. In life prediction with this formula it is unnecessary to choose the constant Q in Miner's formula, therefore its accuracy may be improved.The lives of large components of two aeroplanes and the specimens under five different loading conditions are predicted by this analogy method. The results are quite consistent with fatigue test results and the comparison is shown in tables （ 4 ） and （ 3 ）. This demonstrates that the formula presented in this paper is more accurate, particularly for components analogous to given ones, and may give quite satisfactory results provided the value of the m is estimated appropriately. According to Miner's theory it is possible to apply this analogy method to components different from given ones, but it is necessary to make appropriate correction in actual use.