In this paper, first the fundamental concept of nano-optical biosensing is studied. Since Raman scattered signal is very weak to be recognized by current measuring equipments, the signal must be amplified. SPR and LSPR are utilized to enhance the incident field of the target molecules, to improve the sensitivity of the sensor. The paper focuses on the use of LSPR to enhance Raman signal in SERS technology. Different structures of nano-particles in LSPR to improve enhancement of the SERS signal are reviewed and compared.