The present disclosure provides a method for preparing inorganic nanoparticle-gelatin core-shell composite nanoparticles, comprising: dissolving gelatin in a aqueous solution (in which inorganic nanoparticles are dispersed in) to obtain the gelatin-contained aqueous solution, dropwise adding a polar organic solvent to obtain a suspension of inorganic nanoparticle-gelatin core-shell composite particles of nanometer size or submicrometer size, then adding a cross-linking agent thereto to cross-link the gelatin components of the composite particles, followed by washing step to finally obtain inorganic nanoparticle-gelatin core-shell composite micro/nano-particles with inorganic nanoparticles as the core and gelatin as the shell. The present invention firstly provides a process for preparing the core-shell composite nano-scaled particles with inorganic nanoparticles as the core and gelatin as the shell by using a co-precipitation method which is simple and convenient, and beneficial for applying to industrial mass production.