A 3-year stationary field experimentwas carried out to explore soil phosphorus desorption characteristics and their effects on phosphorus concentration in percolating water from fields under the garden bean ( Phaseolus vulgaris)– zucchini ( Lagenaria siceraria)–paddy rice rotation system, as affected by P application rate, and a model and indices for their evaluation as well. Results show that the model the authors designed fit quite wellsoil P desorption process varying with water/soil ratio. With the aid of the model it was feasible to acquire simultaneously P desorption characteristics, like amount of desorbable soil P(Q) and soil solution P concentration (C_li) and its buffer coefficient (b). The concentration of total phosphorus in the percolating water in the field under the vegetable-vegetable-rice rotation was on average only 42.6% of that in the field under vegetable-vegetable rotation. The relationship between Q and concentrationof total P in percolating water in the field fit the dynamic characteristics of “dual rate turning point”. The turning point X₀of soil P loss characterized by Q varied very slightly and averaged to be 24.4 mg kg^-1, no matter the field was under the vegetable-vegetable-rice rotation or vegetable-vegetable rotation. It could, therefore, be concluded that the vegetabe-vegetable-paddy rice rotation system is conducive to reducing the concentration of total P in percolating water, and the dual-rate turning point X₀ of the amount of soil desorbable P may be used as one of the indices to characterize the potential of soil phosphorus leaching loss in vegetable fields.