This article focuses on the shortcomings of commonly used reducing methods that cannot effectively separate noise when noise and signal boundaries reach a certain balance. A Raman spectroscopy digital reduction technology based on phase-locked technology is studied, which includes modulating the output light intensity of the laser with a sine wave, using an optical system to read and separate the Raman signal, and then using phase-locked filtering technology to achieve the purpose of reducing. The research results indicate that compared with traditional Raman spectroscopy reducing techniques, this technique adopts a separation before detection approach, which avoids the balance between noise and signal boundaries that traditional reducing algorithms cannot balance at the root, and can effectively improve the signal-to-noise ratio of sample Raman signals. By reducing the spectrum of acetaminophen, it can be observed that the noise signal in the sample spectrum is significantly eliminated, and the signal-to-noise ratio is increased by 10 times. This method is universal and particularly helpful for detecting weak Raman signals.