This paper is to study the iso-butane (A-31)-driven salbutamol sulfate (SS) metered dose inhaler (MDI) formulations and inhaling status in guinea pigs.  Solubility determination and orthogonal design were used to screen non-chlorofluorocarbon (CFC) SS MDI formulations.  Intubation inhalation of MDI in guinea pigs was useded as a main administration method.  Fluorescence HPLC detection method was testified as a  potential method in assaying the concentration of SS in plasma of guinea pigs after inhaling various SS MDI  formulations.  Analysis of the data was executed with statistical moment calculation from which pharmacokinetic parameters were obtained.  The results show that A-31 based on SS MDI formulations were screened and the guinea pigs in vivo determination method after inhaling SS MDI was established.  The zero-moment rations of SS/A-31 MDI formulation to contrast sample and CFC SS MDI was 143.26% and 147.01%, respectively.  The first moment value of SS/A-31 MDI formulation was the highest.  It is a preliminary conclusion that the absorption result of SS/A-31 MDI formulation inhaled by guinea pigs is equivalent to HFA-134a formulation in sale and better than CFC formulation.  A-31 could be used as a potential substitute candidate for CFC MDI propellant.