High critical current density. $J_c over 1 MA/cm^2$at 77 K in a self field was successfully achieved from the YBCO film prepared on (100) SrTiO$_3$ single-crystal substrates by the TFA-MOD process. Unlike a normal TFA-MOD process, we prepared the TFA precursor solution by dissolving YBCO powder into the trifluoroacetic acid. A significant amount of the second phases, including $BaF_2$, was observed in the films fired at 700-7$25^{circ}C$ for 2 h under $P(O_2)=10^{-3}$ atm and P($H_2O$)=4.2%, most probably due to an insufficient reaction time, and hence T$_{c}$ was greatly degraded. However the films fired at 750-80$0^{circ}C$ for 2 h were composed of strongly c-axis oriented YBCO grams without any second phases. and exhibited the $T_c$ values of 89.5 ～ 91 K with a sharp transition. With increasing the firing temperature from 750 to 80$0^{circ}C$ average grain size of YBCO was increased and grain connectivity was enhanced. The highest $J_c value of 1.1 MA/cm^2$ was obtained from the YBCO film fired at 80$0^{circ}C$.>.