In this paper,the mean first-passage time (MFPT) in a biased mono-stable system is investigated on the basis of the theory used in an asymmetric bistable system. The effects of parameters on MFPT are also analyzed based on the generalized potential function. The results show that, first,with parameter a and additive noise intensity Q increasing,the MFPTs in two directions both decrease on condition that bias parameter b is equal to zero; second,the time in which the particle jumps from xs1 to xs2 linearly decreases while the time in which the particle jumps from xs2 to xs1 linearly increases,owing to the fact that the symmetry of potential well is broken by the increase of bias parameter b; finally,the MFPTs in two directions monotonically increase as the ratio of multiplicative noise intensity to the additive noise intensity increases.