Five selected China IT business incubators are studied with grounded theory, after coding the interview data, we establish the model of influence factors that affect IT business incubator’s incubation performance with dimensions of the external factor, the internal factor and the associated factor. The external factors that affect the incubation performance are institution and industry environment, the internal factors are network operation ability, capability of incubating service and organization system protection, the associated factor is entrepreneurship of incubated enterprises.