The language use of a family reflects the linguistic characteristics of the region. Adopting the method of sociolinguistic field investigation, this research collects the Chongqing dialectic phonetic materials of three generations of a Chongqing family, analyzes their initials, finals and tones, studies the evolution trend of the pronunciation of Chongqing dialect, and finally explores the factors that lead to the evolution trend. The survey found that it is not salient that the intergenerational phonetic happens, only some typical old-style pronunciations transfer in the third generation: the initials /f//h/ can be distinguished; the final /o/ gradually moves closer mandarin sound /e/; the level tone tends to move towards that of Putonghua. Investigating the reasons, it is found that objective and subjective factors such as pragmatic frequency, educational level, language environment, identity, language ardor, and so on have contributed to the current situation of the phonetic evolution of Chongqing dialect.