1. A method for optimization of fuel cells operating conditions using a hybrid model, comprising: generating a theoretical performance model by obtaining a potential difference depending on a current density of a cell based on a thermodynamics reversible voltage, an activity loss, a resistance loss, and a concentration loss of a high temperature proton-exchange membrane fuel cell (PEMFC) which is based on a polybenzimidazole (PBI) membrane with which phosphoric acid is doped (S 10 ); generating an empirical durability model by performing a long-term durability test which is performed for a predetermined period under experimental conditions (operating conditions) specifying the high temperature PEMFC based on the PBI membrane with which the phosphoric acid is doped, so as to predict the reduction in cell voltage over an operation time at a predetermined temperature (S 20 ); generating a life prediction model determined by time and temperature based on the performance model generated in the generating of the theoretical performance model (S 10 ) and the durability model generated in the generating of the empirical durability model (S 20 ) (S 30 ); and estimating an optimal operation temperature at a target life based on the life prediction model generated in the generating of the life prediction model (S 30 ) (S 40 ).