The passive safety features for spacecraft in close relative hovering with respect to circular reference orbit were analyzed by solving the minimum relative distance during the free motion with zero initial velocity. The passive safety features of spacecraft relative hovering can be described as the state of empty intersection between the relative motion trajectory and the target′s no-fly zone after the disappearance of the control force. This problem can be by transformed into the problem of minimum relative distance with zero initial velocity. The minimum relative distance varies with the initial position, and may be located in the integer period minimum value or the non-integer period minimum value point. The existence conditions of two kinds of minimum value points were analyzed. Then the calculation method of critical passive safe hovering area was obtained by solving the boundary condition in two cases. For the typical relative hovering scenario, the critical safe hovering area under the constraint of plane circle and three-dimensional spherical no-fly zone was simulated and analyzed. The effects of model error and J₂ perturbation on hovering passive safety features were evaluated. This analysis method can provide consultation for hovering mission design with passive safety features.