Abstract: A new method was applied to study the shrinkage characteristics of briquette during pyrolysis by realtime online images collection and computer image processing. The swelling and shrinkage characteristics of the briquette with different density were monitored using a digital camera during pyrolysis. Transient swelling and shrinkage phenomena were observed, and quantifative swelling and shrinkage were measured by computer images processing. The results show that the briquette begins to shrink at 400℃, and has two shrinkage ranges at 400℃~550℃ and 650℃~800℃. The lateral shrinkage and volume shrinkage decrease with the increase of briquette densities. The lateral shrinkage and the volume shrinkage were 12%~18% and 32%~44%, respectively at 1000℃ for 4 briquette samples with different densities. The volume shrinkage relates to sample contents of both the volatile matter and the ash. Generally, the volume shrinkage at 1000℃ increases linearly with the increase of the volatile matter or the decreas of the ash content of briquette samples.