The invention discloses a water-based tape casting method for sheet-shaped positive temperature coefficien heat-sensitive ceramics. The method comprises the following steps: 1) adding deionized water and dispersing agent in nano-sized BaTiO3-based positive temperature coefficient heat-sensitive ceramic powder, and mixing by a ball mill for 3-5 hours to obtain a BaTiO3 slurry; 2) adding binder andplasticizer in the BaTiO3 slurry, mixing by the ball mill for 2-3 hours, and sieving to obtain a water-based casting slurry; 3) performing casting treatment of the water-based casting slurry, drying the wet film obtained after casting treatment to obtain a ceramic blank; and 4) cutting the ceramic blank to square shape and sintering to obtain sheet-shaped positive temperature coefficien heat-sensitive ceramic. The produced ceramic blank has smooth surface, high strength, good flexibility and adaptivity for winding and curling. The produced sheet-shaped positive temperature coefficien heat-sensitive ceramic is widely used for the overcurrent protection and overheat protection in the fields of portable mobile telephones, high-resolution color televisions, auto electronics and hybrid integrated circuits.