The invention belongs to the field of cross-linking high-molecular polymers, and in particular relates to cross-linking polyglutamic acid suspension as well as a preparation method and application thereof. The preparation method of the cross-linking polyglutamic acid suspension comprises the following steps: (1) adding a cross-linking agent into deionized water, uniformly stirring, further adding polyglutamic acid and/or polymeric glutamate, uniformly stirring, and keeping the temperature, so as to obtain a premix; (2) adding deionized water into the premix for homogenation; (3) adding 0.6-7.5 parts of a glutamate compound into a homogenation product, and uniformly stirring, thereby obtaining the cross-linking polyglutamic acid suspension. The preparation method is simple to operate and easy in industrial production; the viscosity degradation amplitude of the cross-linking polyglutamic acid suspension prepared by using the preparation method is less than 10% after 12 months, and the viscosity is not conspicuously degraded in subjective feeling; the cross-linking polyglutamic acid suspension provided by the invention can be used in sticky moisturizing and beautifying toner which has the characteristic that three effects of stickiness, moisturizing and beautifying are integrated.