The invention belongs to the technical field of nuclear power maintenance, and particularly relates to a chemical cleaning method used for a secondary loop valve cage. The method comprises the steps of using an alkaline solution for soaking and cleaning of the secondary loop valve cage; using water for cleaning the secondary loop valve cage which is soaked and cleaned by the alkaline solution; when a residual alkaline solution on the secondary loop valve cage is cleared, using an acid solution for soaking and cleaning the secondary loop valve cage; using water for cleaning the secondary loop valve cage which is soaked and cleaned by the acid solution; when a residual acid solution on the secondary loop valve cage is cleared, using a passivating agent for passivating the secondary loop valve cage; using the water for cleaning the passivated secondary loop valve cage until a residual passivating agent on the secondary loop valve cage is cleared; and when the residual passivating agent onthe secondary loop valve cage is cleared, drying the secondary loop valve cage. The secondary loop valve cage can be rapidly and thoroughly cleaned, and the mechanical damage to the secondary loop valve cage can be little.