A new method for studying excited state nonlinear absorption through measuring the temporal profile of input and output single laser pulses was presented. Using this method, the transient excited state nonlinear absorption of the solution of cadmium texaphyrin like in chloroform ((TXP)Cd) and the solution of methyl orange are demonstrated by the ns laser pulse. The reverse saturable absorption in (TXP)Cd and the combination of saturable absorption and reverse saturable absorption in methyl orange are observed, respectively. The theoretical simulations agree well with the experiment results.