Abstract: The vacuum failure of receivers has always been the main problem in parabolic trough solar power stations. Its vacuum performance directly affects the efficiency and economy of the whole system. In this paper, a new portable non-destructive testing method based on spark discharge and emission spectroscopy is proposed to evaluate the vacuum performance of receivers. Aiming at the four most common high-purity gases(hydrogen, helium, nitrogen, and argon) and their mixtures in the annulus of receivers, the discharge characteristics and spectral characteristics are detected. The fitting law between the spectral intensity of each gas characteristic peak and the air pressure is obtained and verified. The results show that this method can accurately obtain the gas type and pressure,and the pressure measurement range can be extended to 0.5 Pa. The whole detection device is portable and suitable for online application in a trough solar heat collection system or power generation system. The device's non-destructive vacuum performance test of the receivers will play an important guiding significance for improving the system efficiency and reducing the operation and maintenance cost.