A stochastic version of the delayed SIS epidemic model with vaccination was concerned.A simple but effective method was provided for estimating the threshold of a class of stochastic epidemic models by use of the nonnegative semimartingale convergence theorem.The threshold of the stochastic delayed model,denoted by R₀,completely determines the extinction and prevalence of the disease.If R₀<1,the disease ultimately vanishes from the population with probability one.If R₀>1,the system is proved to be convergent to a point in the meaning of time mean.