Abstract: With the intensification of soil heavy metal contamination, it is of great practical to explore ways to improve the soil remediation efficiency by hyperaccumulator plants. To reveal the effects of uniconazole (S3307) on the growth and heavy metal accumulation of hyperaccumulator plants, pot experiment was conducted to study the effects of spraying S3307 solution with different concentrations(0, 25, 50, 75, 100 and 125 mg·L^-1) on the growth and cadmium accumulation of two ecotypes (farmland and mining) of Bidens pilosa. The results show that S3307 inhibited the growth of both the two ecotypes of Bidens pilosa by significantly decreasing the biomass and plant height. Compared with the control, S3307 significantly increased the photosynthetic pigment (chlorophyll a, chlorophyll b and carotenoid) contents and cadmium contents in two ecotypes of Bidens pilosa. When the concentration of S3307 was 125 mg·L^-1, the cadmium contents in the shoots of farmland and mining ecotypes of Bidens pilosa got the maximum, which were 91.44% and 77.79% higher, respectively, than the control. For the cadmium accumulation amount of Bidens pilosa, the cadmium accumulation amount by the shoots and whole plants of two ecotypes of Bidens pilosa got the maximum when the concentration of S3307 was 25 mg·L^-1. The suitable concentrations of S3307 could effectively improve the remediation ability of farmland and mining ecotypes of Bidens pilosa to cadmium-contaminated soil, and the best dose is 25 mg·L^-1.