In the present work, the effect of dust on the efficiency of an Evacuated Tube Solar Collector was investigated experimentally and theoretically. Experiments were performed on Evacuated Tube Solar collectors exposed to the ambient winter season in Minquin, China from 8 to 18h00. A mathematical model used for two modules, one present dust accumulation of 0 mg/m2 (clean collector) and 2.6E-05 mg/m2 (dusty collector with 15.24 % of the reduction in radiation). The ASHRAE Standard 93-86 was used to calculate the efficiency. The results show in comparison with and without dust, the daily optical efficiency decrease of 17.6 % and the average stagnation temperature decreases from 7.30C–1.80C in a solar collector with 2.6E-05 mg/m2.