The present invention discloses a small tip-enhanced Raman spectrum measurement device and a detection method thereof. The device comprises a laser light source module, a dichroscope, an auxiliary calibration module, an objective lens and a three-dimensional translation stage which are sequentially arranged along a light path, and further comprises a long-pass optical filter, a laser focus lens and a spectral signal acquisition module which are sequentially arranged on the transmission side of the dichroscope, and a control and data processing module which is connected with the auxiliary calibration module, the three-dimensional translation platform and the spectral signal acquisition module. According to the scheme, a white light illumination and microscopic imaging light path, an excitation and collection light path and a Raman spectrum light path are organically integrated together, a sample, a needle tip and laser are accurately coupled by utilizing the white light illumination and microscopic imaging light path before measurement, the maximum excitation efficiency is realized, and the excitation and collection light path is directly coupled with the Raman spectrum light path, so that the loss of a peripheral light path in the measurement process is reduced, and the structure size of the whole measurement device is reduced while the spectral resolution capability is ensured by optimizing the light path structure of each part.