Equilibrium geometries,electronic and magnetic properties of M_n(SiO₂)₃(M= Fe,Co,Ni;n=1-3) clusters are systematically studied employing density functional theory with a generalized gradient approximation. It shows that Fe and Co atoms are easier to congregate on (SiO₂)₃ cluster than Ni atoms. It is found that stabler silica is an excellent matrix materials to carry islands of transition-metals. Energy gaps of M_n(SiO₂)₃(M=Fe,Co,Ni;n=1-3) clusters lie in near infrared radiation region. In analysis of magnetism,it is found that their magnetic moments are mainly located on transition-metal atoms. Fe₂(SiO₂)₃ and Co₃(SiO₂)₃ have greater magnetic moments,owing to coupling between d orbits of transition-metal atoms. Energy gap and magnetic property affirm a considerable foreground of magnetic-mulriple silica used for photodynamic target therapy in medical stage.