A method for evaluating phase stability of an electrode mixture slurry, including the steps of: (S1) introducing the electrode mixture slurry to a rheometer; (S2) applying a first shear rate to the electrode mixture slurry; (S3) applying a second shear rate after applying the first shear rate to the electrode mixture slurry, wherein the second shear rate is higher than the first shear rate; (S4) applying a third shear rate after applying the second shear rate to the electrode mixture slurry, wherein the third shear rate is lower than the second shear rate; and (S5) comparing the shear viscosity at the first shear rate with the shear viscosity at the third shear rate. An apparatus for evaluating phase stability of the electrode mixture slurry is also provided.