Abstract: An emittance measurement instrument based on embedded system was introduced. The instrument was based on slit-wire method. It had seven different measurement ranges, and its data sampling rate was up to 200 kHz. The system construction and working principle were discussed. The design and production of the data acquisition system were also discussed. The analog signal circuit was established by using high-speed, low-noise integrated chips, along with appropriate resistors and capacitors. The filters in every stage, the low-noise power supply technology and the shielding technology insure the realization of a low-noise data acquisition circuit. The results of tests show that the acquisition accuracy is 1.47% at the measurement range of 10 nA, and up to 0.32% at the range of 1 A. The harmonic distortion is 6.5 dB when a sine wave is sampled with the frequency of 20 kHz. The fastest movement speed is 3.125 mm/s at the movement accuracy of 1.25 m.