To solve the problem of material emissivity measurement at medium-high temperature, a high-temperature material spectral emissivity measurement technology based on semi-ellipsoidal reflector is proposed. In this technology, a 800 mm semi-ellipsoidal mirror is used to focus the signal light in a large range, three kinds of off-axis parabolic mirrors are used to switch different test fields of view, and the sample is heated by a high-power laser. The measurement error of the designed system is studied in simulation. The results show that the maximum measurement deviation of reflectivity is 0.035, and that of transmittance is 0.031. An emissivity measurement system based on a 800 mm semi-ellipsoidal mirror is constructed. Then, the reflectivity, transmittance, and emissivity of an alloy material and a translucent material are measured, which shows that the designed system can realize the measurement from normal temperature to medium-high temperature (300--1200 K), multi-field of view (30°, 60°, 90°), and wide spectrum (2--14 μm).