The invention discloses a method of detecting a metal capsulated internal molecular signal based on a tip-enhanced Raman spectroscopy technology. The method is characterized by comprising the following steps of A. synthesizing a gold nano triangular sheet: A1, performing hydrothermal treatment on chloroauric acid by using a surfactant cetyl trimethyl ammonium bromide; A2, performing centrifugal separation on a reaction product obtained in step A13 by using a centrifuging machine, and washing and settling by using ultra-pure water; A3, repeating the step A2 three times to obtain the gold nano triangular sheet; B. preparing a capsulation structure of the gold nano triangular sheet: B1, sputtering a layer of metal membrane on the surface of a silicon sheet; B2, soaking the metal membrane in a4-nitrothiophenol molecular alcohol solution, then washing with alcohol and ultra-pure water in sequence, and then drying with nitrogen gas; B3, spin coating the metal membrane with a glue solution of the gold nano triangular sheet, and allowing the glue solution to volatilize naturally; C. detecting an internal molecular Raman signal in a capsulated structure of the gold nano triangular sheet. The method can be widely used in production and detection of micronano devices.