Piperazine (PZ) as an additive was added into a solution of potassium citrate (PC) to form a novel complex solution of the aqueous (PC + PZ) system. Research for the physical properties, density, viscosity, and surface tension, of the aqueous (PC + PZ) system was carried out. Densities and viscosities of the aqueous (PC + PZ) system have been determined at (293.15, 303.15, 313.15, and 323.15) K, and surface tensions of the aqueous (PC + PZ) system have been measured at 293.15 K. Correlations for the physical properties were fitted using the method of mathematics. Predictions of the physical properties of the aqueous (PC + PZ) system were conducted. Performances were compared and discussed between the (PC + PZ) system and other complex systems such as the (PG (glycinate) + PZ) system. Results show that the densities and viscosities of the aqueous (PC + PZ) system decrease with the increase of temperature and PZ mole fraction in the system. The surface tensions of the studied system decrease as the PZ mole fraction in the system increases at 293.15 K. The physical properties of the aqueous (PC + PZ) system are basically similar to that of the aqueous (PG + PZ) system. As opposed to the (PG + PZ) system, the viscosity of the aqueous (PC + PZ) system decreases, while the viscosity of the aqueous (PG + PZ) system increases as the PZ mole fraction in the system increases. The surface tension, of the aqueous (PG + PZ) system decreases linearly, while the surface tension of the aqueous (PC + PZ) system is nonlinear with the increase of PZ mole fraction in the system. The prediction values from correlations for the physical properties are in good agreement with the experimental values. The correlations for the physical properties of the aqueous (PC + PZ) system can offer additional data.