Abstract: In order to solve the main problems of the laser-induced fluorescence detection system, such as complex optical structure, large volume, high cost and insufficient sensitivity, a sensitive and miniaturized fluorescence spectrometer was proposed. The spectrometer used a 349 nm semiconductor laser as the excitation light source, adopted an orthogonal optical path, coupled a 4×4 narrowband filter array and a silicon photomultiplier (SiPM) array with single photon sensitivity, which could realize multi-channel detection of spectral information. It had the advantages of compact structure, low cost and good stability. Sodium fluorescein was used for performance evaluation of the spectrometer. The experimental results show that the detection limit of the spectrometer is better than 5×10⁻¹¹ mol·L⁻¹. The linear correlation coefficient of the fluorescence intensity is 0.998 39 with the concentration from 5×10⁻¹¹ mol·L⁻¹ to 1×10⁻⁹ mol·L⁻¹. In addition, the spectrometer also has good repeatability, and the relative standard deviation of the fluorescence peak intensity is less than 10%. Therefore, the spectrometer has the advantages of high sensitivity, good linearity, strong repeatability and reliability, and can meet the needs of on-site real-time detection.