Abstract: This experiment is to study the relationships between nutrient contents and physical properties of swine slurries in order to estimate fertilizer value of swine slurries. Analytical results of this paper show that slurry fertilizer value can be estimated by two main physical parameters: electrical conductivity (EC) and specific gravity (SG). Electrical conductivity (EC) can be evaluated for estimating ammoniacal nitrogen in pig feces, in pig urine and in pig manures; Electrical conductivity (EC) can be evaluated for estimating potassium in pig feces, in pig urine and in pig manures; specific gravity (SG) can be evaluated for estimating total nitrogen in pig feces, in pig urine, in pig manures and phosphorus in pig manures. Furthermore, the linear regression equations of total nitrogen in pig urine and electrical conductivity (EC) provide reliable and accurate indication of total nitrogen content in pig urine.