P leaching and transport in paddy soil has been a public concern for a long time. A lab leaching experiment was conducted to study P leaching and vertical transport in paddy soil after P was applied to tested paddy soil. Results showed no significant influence of P application on P concentration in leached-water samples obtained by 60 cm high soil-filling lysimeters in different treatments; P concentrations of different fractions of leached-water samples were all less than 0.1 mg/L, equal to 1.2~1.4 kg/hm² of dissolved reactive phosphorus (DRP), 1.2~1.6 kg/hm² of unreactive phosphorus (UP) and 2.5~2.8 kg/hm² of total phosphorus (TP) lost from tested soil, respectively, thus, could influence little on groundwater; P did not transport to subsoil as P applied amount less than 400 kg/hm², but an obvious P transport was found as P applied amount above 800 kg/hm², which could reach 10 cm when P applied amount above 1600 kg/hm²; 74.1 mg/kg was forecasted as threshold of Olsen-P in top soil to leach and transport to subsoil, and possibility of P leaching and transport would increase if P concentration beyond it.