This work presents the isolation of Low-Density Lipoprotein (LDL) from blood. The blood molecules with size less than 1µm are filtered in the size based crossflow filter technique. Filtered molecules are passed through the Porous Silicon (PSi). The immobilized Anti-Apolipoprotein B (AAB) on the surface of Porous Silicon is used to adsorb the LDL. Isolation of LDL based on Porous Silicon eliminates the calculation of the other lipoproteins and Triglycerides. Filter with AAB coated PSi is designed and simulated in COMSOL Multiphysics software.