The invention relates to a passive radial supporting mechanism for a
primary mirror of an
optical telescope based on kinetic equilibrium. One end of a first-stage connecting rod of the mechanism is hinged with the rim of a
primary mirror chamber, and the other end of the first-stage connecting rod is hinged with a second-stage connecting rod and a third-stage connecting rod at the same time; the other end of the second-stage connecting rod and the other end of the third-stage connecting rod are hinged with the rim of the
primary mirror; and an included angle theta is formed between the second-stage connecting rod and the third-stage connecting rod. By a kinetic equilibrium
system, the radial direction of the primary mirror is not restrained by an over-restraining characteristic, so that a
stable equilibrium state is realized; when temperature is changed, the whole radial
supporting system does
micro motion in accord with a kinetic rule by using the change of the geometric size caused by
thermal deformation of a connecting rod mechanism, so that stress caused by the
thermal deformation among the primary mirror, the radial supporting mechanism and the primary mirror chamber is counteracted; therefore, the passive radial supporting mechanism is suitable for supporting primary mirrors made of materials with large
thermal expansion coefficients and primary mirrors working under a relatively severe
working environment.