Raman spectrum of pyridine has been investigated at high hydrostatic pressure, the pressure behavior of the vibration modes below and above phase transitions has been studied. A kind of crystalline-plastic phase transition was observed near 60 kbar. A satellite peak at the high frequency side of the ring breathing mode 992cm-1 was detected, which shifted more rapidly to ward high frequency with pressure. It is supposed to be the ring breathing mode of adsorbed (interface) molecules on the surface of ruby particles which was used for pressure calibration. The satellite is extremely enhanced, possibly by a mechanism of Mie structure resonance scattering.