In recent years, nitrogen vacancy (NV) centers in diamonds have been widely and intensively investigated due to their unique solid-state spin system, excellent ultra-high magnetic sensitivity, spatial resolution, long decoherence time and fluorescence stability. Based on the long spin coherence time and manipulable and readable electron spin states of NV centers, it is regarded as one of the most promising quantum sensor materials for quantum computing, weak signal (magnetic and electric field) detection and temperature measurement, and shows great potential for applications in quantum sensor research. This paper focuses on the study of modular magnetometer based on diamond NV centers. The crystal structure and energy leap properties of the NV centers, the quantum manipulation principle of the magnetometers, and the solution to the problems of the traditional fluorescence spectral acquisition system and optically detected magnetic resonance (ODMR) spectral acquisition systems, such as cumbersome construction, the low focusing accuracy of the detected samples, difficulty in the conversion between the acquisition systems, and the ODMR spectral acquisition signal, are introduced. We designed an optical fiber sensing-based fluorescence acquisition and ODMR spectral acquisition conversion system to address the problems of low signal-to-noise ratio and low acquisition accuracy of ODMR spectral acquisition. The system is designed to integrate the excitation light source circuit, microwave sensing antenna, fiber optic sensor, microscope focusing optical path, PD (photodetector) amplification circuit, signal processing module and fluorescence spectrometer modules through fiber optics, which provides hardware support for the software part of signal processing. In the software part, the signal data processing and spectral imaging functions are realized by open-source programming. After the initial processing of the data by the PD amplifier circuit, the data are further processed by the signal processing module in the software part, and the data are presented in the form of a spectrum, and the final magnetic sensitivity reaches 0.51nT/Hz1/2.