To study the imaging characteristics of ultrasound biomicroscopy of secondary pupillary block glaucoma.11 cases with pupillary block glaucoma diagnosed by ultrasound biomicroscopy were studied which had been suspected as malignant glaucoma at the beginning.There were no obviously typical characteristics of pupillary block glaucoma shown in the images of ultrasound biomicroscopy in these cases. However, the existence of posterior chamber in each case strongly supported the diagnosis of pupillary block glaucoma. The imaging characteristics of ultrasound biomicroscopy were different in terms of the different primary disorders which resulted in the pupillary block glaucoma including iridocyclitis, lens subluxation resulted from trauma and glaucoma filtration surgery. In the cases of lens subluxation, the main characteristic was the increase of the distance between the lens and the ciliary process at the site of subluxation and the lens forward movement. In the cases of iridocyclitis, anterior and posterior synechiae were the main characteristics. And in the cases of glaucoma filtration surgery there were two main characteristics. One was that the distance between the ciliary process and the equator of lens existed obviously, and the other was the occlusion of the inner ostium of glaucoma filtration surgery or peripheral iridectomy.Ultrasound biomicroscopy (UBM) has important value in the diagnosis of secondary pupillary block glaucoma and the differentiation between it and malignant glaucoma. Whether the posterior chamber exists or not is the differential point between the pupillary block glaucoma and the malignant glaucoma.