This paper concerns about the safe approaching in rendezvous with spherical envelops of spacecraft. Based on the nonnegative characteristic of positive systems, a novel strategy of controlling the relative distance positive and convergent is proposed to guarantee no‐collision approaching. The dynamics of the relative distance is decoupled from that of the relative angles. A nonlinear disturbance observer is designed, and two anti‐disturbance controllers are constructed to reject the effect of disturbances for the subsystems of relative distance and angles. Under the controllers, the closed‐loop subsystem of relative distance is a positive and stable system, while that of relative angles is a general stable system satisfying the given time‐varying constraints. Particularly, a theorem is proposed to present the conditions of controllers to ensure the system positivity under a class of external inputs without nonnegativity default. Finally, simulation results are presented to illustrate the effectiveness of proposed methods.