The invention discloses a high-performance lead-free negative temperature coefficient temperature-sensitive thick film and a preparation method thereof. Major composite components are combined in two combination modes. In an inorganic phase I combination mode, (1-t)Ba1-yMyFe1-xSnxO3+tBaCozCo2zBi1-3zO3, wherein t is more than or equal to 0.4 and less than or equal to 0.95 and is a molar ratio; and in an inorganic phase II combination mode, (1-m-1)Ba1-yMyFe1-xSnxO3+mBaCozCo2zBi1-3zO3+1/2Ag2O, wherein m is more than or equal to 0.3 and less than or equal to 0.65; l is more thanor equal to 0.05 and less than or equal to 0.3; m and l are molar ratios; and the composite components are uniformly mixed with an organic carrier in the mass ratio of 75:25 so as to form thick film resistance paste. The preparation method comprises the following steps of: printing the paste on a substrate by a screen printing process; flattening, baking, pre-sintering and repeatedly printing so as to obtain a thick film biscuit with a required thickness; and sintering the biscuit at the temperature of between 750 and 850 DEG C and preserving heat for 40 to 80 minutes so as to obtain the lead-free negative temperature coefficient temperature-sensitive thick film. The thick film has a simple preparation process and a low film forming temperature, the film thickness is between 10 and 100 mum, the temperature sensitive constant value is between 2,500 and 5,500 K, the room temperature resistivity is between 150 ohm.cm and 10 M ohm.cm and the aging resistant time is over 800 hours.