A spectral data acquisition system is designed based on NMOS linear image sensor and micro controller unit (MCU) technology. The hardware and operating principle of this system are introduced, and the structure, principle and characteristics of S3924-512Q image sensor are analyzed in detail. Data acquisition of spectral signal is realized by A/D conversion controlled by PIC16F877A MCU, and flowchart of the program is given. Using this system, spectral acquisition of the specific band with high precision is achieved.