The process of apoptosis of BHK-21 cells induced by Sindbis virus (SbV) infection is reported here in details. The nuclear DNA cleavage can be first detected at 6 h after SbV infection, followed by the chromatin margination and condensation at 12 h and the DNA ladder can be detected at 24 h after infection. The details of apoptosis body's formation can be revealed by electron microscopy: First, the outer nuclear membrane protrudes where the condensed chromatin accumulates, then the chromatin get into the budding area with the inner nuclear membrane and separate from the nuclear. Progressively, we cloned the gene of SbV nonstructure protein 2 (nsP2) into the eukaryotic expression vector pMAMneo, and it can be expressed transiently. The DNA cleavages, the basic characteristics of apoptosis also can be detected in some cells. Together with the sequence analysis of nsP2 and the other former results, we conclude that the nsP2 may have direct relation with the SbV-induced apoptosis.