To study the emissivity spectrum characteristics of high-temperature targets in the short-wave infrared band and the correlation law between emissivity and temperature, a high-temperature graphite plates is measured using a spectrometer in a darkroom environment, and its surface is measured using a thermocouple based on the black body radiation law. Spectral emissivity of the high-temperature graphite plate in the short-wave infrared band (1300--2500 nm) at nine different temperatures is obtained. At the same time, the variance analysis method is used to analyze the differences in emissivity at different temperatures. The experimental results show that the shape of the emissivity spectrum curve is the same at different temperatures. The emission valley and emission peak appear at the wavelengths of 2200 and 2380 nm, respectively. As temperature increases, emissivity tends to decrease. In case of a confidence level of 0.05, the emissivity of different temperatures is significant; emissivity changes with temperature. In the temperature range of 559--855 K, the value of the emissivity from 0.77--0.83 to 0.62--0.70. The change law can be fitted with a linear model, and the coefficients determination are all greater than 0.87.