[Objectives] Exploring the effects of different particle sizes (50, 200 and 1 000 nm) and different concentrations (zero, low, moderate and high) of fluorescent polystyrene microsphere solutions on the body size and internal organ indices of Pelophylax nigromaculatus at Gosner stage 37 tadpoles. [Methods] The Gosner stage 37 tadpoles were exposed to any combination of any particle size and any concentration solution for 7 days, then were transfered into dechlorinated tap water and fed without fluorescent polystyrene microsphere solution for an additional 7 or 14 days. The variations of ratio of body mass to total body length (ratio of BM to TBL), the length of small intestine, and the wet masses of heart and liver were continuously measured. All statistical analyses were performed using SPSS software packages (SPSS 19.0 for windows). For any particle size (50, 200 or 1 000 nm), two-way ANOVA (concentration × day) and multiple comparisons were used to compare the differences of ratio of BM to TBL, the length index of small intestine, and the wet mass indexes of heart and liver. Then, one-way ANOVA and multiple comparisons were further used to compare the differences of the parameters mentioned above among different concentration groups from the same day, or among different days from the same concentration group. Results were presented as means ± standard error, and P < 0.05 was considered to be statistically significant. [Results] Ratio of BM to TBL was not affected by polystyrene microsphere exposure and clearance under the conditions of 200-nm solution (Table 3, P > 0.05); The BM to TBL ratio was significantly lower in clean water group than that of any other concentration group on day 14 when exposed to 50-nm solution (Table 2, P > 0.05); When exposed to 1000-nm solution, the ratio was significantly higher on days 7 and 14 than on day 21 for moderate concentration group, which was lower in high concentration group than that of any other concentration group on day 7, and was higher in clean water group and low concentration group than that of moderate concentration group on day 21 (Table 4, P < 0.05). When exposed to 200-nm solution with high concentration, small intestine length index was significantly changed with days, being greatly increased from day 7 to day 14, and sharply declined by day 21 (Table 3, P < 0.05); On day 7 or 14, exposure to 1 000-nm solution with moderate concentration, the index was greatly higher than on day 21, while it was greatly lower in high concentration group than that of any other concentration group (Table 4, P < 0.05), but not for 50-nm (Table 2, P < 0.05) or 200-nm solution group (Table 3, P < 0.05). The wet mass indexes of heart and liver did not greatly change (Table 2﹣4, P > 0.05); The heart wet mass index was only significantly changed under the conditions of 50-nm solution on day 14, which was highest in clear water group, followed by high and moderate concentration groups, and lowest in low concentration group (Table 2, P < 0.05); The liver wet mass index was only significantly lower in clean water group than that of any other concentration group on day 14 from 50-nm or 200-nm solution group (Table 2 and 3, P < 0.05). [Conclusion] Ratio of BM to TBL, indexes of heart and liver wet masses, small intestine length index combined with liver wet mass index, and ratio of BM to TBL combined with small intestine length index were affected by 50-nm, 200-nm or 1000-nm polystyrene microspheres solution, respectively, but polystyrene particle size and concentration are not linear with their potential hazards.