The traditional exposure methods of shortwave infrared focal plane spectrometer have shortcomings in a variety of applications. This paper proposes a balanced exposure technique to eliminate these shortcomings. To improve the signal to noise ratio of the spectrometer, different spectral dimensions are given different integral times. We built an experiment system that included a shortwave infrared focal plane detector, a driver circuit, a signal acquisition and processing circuit, and PC software. The results of five different integral times (3.31 ms, 5.76 ms, 8.22 ms, 10.68ms, 13.14ms) and the contrast between them are close to the theoretical values. We conclude that this exposure technique can significantly improve the signal to noise ratio.