With the blind number theory, the mechanical structure’s time-dependent characteristic based on stochastic process was deduced. The uncertain variables in time-dependent stochastic process of mechanical structure were expressed in blind number, and its time-dependent reliability calculation model based on blind number theory was built. And what’s more, the corresponding program in LabVIEW language was given, and a free beam’s time-dependent reliability was also computed. The result showed that blind number as a kind of numerical tool is very convenient and effective for solving the complicated reliability calculation model.