Abstract: The coal particle size has a significant influence on the combustion and heat-transfer in the CFB boiler. Based on the existing problems of the current coal-screening system in a certain plant, this paper provided a new modification scheme of the cross sieve and its actual effects in engineering application. The results show that after retrofit, the mass fraction of the coal particles larger than 13 mm sharply decreases, and the average carbon content in the bottom slag drops from 3.7% to 2.1%. The new-type cross seive has both a low reform cost and a high screening efficiency. It would play an important part in enhancing the reliability of the screening system in CFB boilers and achieving remarkable economic benefits.