Enterprises invest in training to improve their human capital and generate more rewards.  However, there exist risks simultaneously in the investment.  Training of the staff at different stages of their career may have noticeable differences in rewards and risks.  The inner relationship between characteristics of different career stages and human capital cycle was analyzed.   It is pointed out that when making decisions in staff training enterprises should take into account characteristics of different career stages, for these characteristics are essential to studying the two variables-timing and type of training and to making lowrisk, richreward training investment decisions.