The invention discloses a method for casting a turbine rotor blade of a gas turbine through aluminum oxide ceramic type shells. The method comprises the following steps of: 1) preparing a certain layers of aluminum oxide ceramic type shells on a rotor blade wax mould through a slurry-soaking and sand-spraying method; 2) packaging a blade top part with a wax sheet when a distance between the ceramic shells between blade top sealing teeth is smaller than an anti-adhesion distance; 3) continuously adopting the slurry-soaking and sand-spraying method on the rotor blade wax mould to reach a required shell-making layer number, wherein slurry and sand on the wax sheet on the blade top part are cleaned every time; 4) dewaxing the shell and burning residual wax; 5) preparing a mixed solution of silica sol and aluminum oxide powder; 6) soaking the blade top part into the mixed solution; 7) drying the blade top part at the room temperature; and 8) heating the shell to a temperature of 1400-1500 DEG C and preserving the heat for 0.5-1 hour, and reducing the temperature to a temperature which meets the process requirements to cast. The casting method can prevent the ceramic shells among the blade top sealing teeth from being adhered, avoids generating thermal centers, and remarkably improves casting quality of the rotor blade.