To select the adaptive strain of Dengue-III virus D9964 strain (China strain) in KMB17 cells, elucidate the biological characteristics and proliferation kinetics of adapted strain,and to lay the foundation for the development dengue inactivated vaccine and attenuated live vaccine. Dengue-III virus D9964 strain was firstly identified by amplification of the type-specific gene segment of dengue virus by RT-PCR, and the titer was determined. The virus was then subcultured in KMB17 cells with 4.0 MOI till completely adaptive to multiply in cell S. After subculturing in KMB17 cells for 10 consecutive passages, the adapted strain was screened, and purified through plaque. Virus titer of each passage was measured by microtitrimetry, and the antigenicity was detected by IFA. The purified virus RNA extraction of 3-8 day cultured from KMB17 cells, was performed to detect the proliferation kinetics of adapted strain. The results showed that after continuous subculture, dengue-III virus D9964 (China) strain could stably proliferate in KMB17 cells, a highly puried virus adapted strain was obtained through plaque purification. Purified strain maintained the good antigenicity with a highest replicating activity during the 5th-6th day.