Abstract: According to fundamentals of hydrokinetics and specific conditions of aspiration process, this paper describes the following Poiseuille equation for AAS: Q_L=π·R⁴(P_n-ρgh-P_σ)/8ηL The effects of negative pressure at the spray nozzel (P_n), relative height of solution surface (h), capillary length(L), solution viscosity(η) and additive pressure caused by solution surface tension (P_σ) on aspiration rate (Q_i) were quantitatively and experimentally examined. The experimental results are in agreement with theoretical analysis, ' The agreement indicates that the Poiseuille Equation for AASis reasonable.