This paper introduces a compact data acquisition for micro spectrometer. The system uses a linear CMOS sensor to capture the spectrum, and a single STM32 ARM chip to control, to process and to transfer the signals. Compared with the traditional data acquisition system based on FPGA and ARM chips, this system has smaller size and lower cost, making it suitable for use in micro spectrometer. The performance of the system is also evaluated by a series of experiments. The system shows good linearity and accuracy. The responses under different integration time, different pixel, and different wavelength are also measured, which is important for signal correction in spectrum measurement.