Life history is an important topic in avian ecology, and the determinants of life history traits are important for understanding bird ecological adaption. Comparisons of breeding parameters of Yellow-bellied Prinia Prinia flaviventris and Plain Prinia P. inornata were performed at Jiangxi Village, Zhaoqing, Guangdong, from March to September in 2007. Our results showed that: 1) there were no significant differences in various breeding parameters between two Prinia, except for nest-building period, clutch size, nest predation rate and nest destruction rate (Table 1); 2) Yellow-bellied Prinia had lower clutch size but larger egg size, compared with the Plain Prinia; 3) these two Prinia species had relatively higher annual productivity compared with nine passerine birds of similar body mass (Fig. 2); 4) there was obvious differentiation between two Prinia species in most of breeding parameters, possibly caused by different nest predation risks. Our findings suggested that Yellow-bellied Prinia responded to relatively high nest predation with lower clutch size but larger egg size, while Plain Prinia had higher clutch size but smaller egg size.