A flat ceramic membrane has a separating function and is a novel type of material membrane. High temperature resistance, superior mechanical strength, huge permeation flow, and reusability are all advantages. It’s been employed in water treatment industries like food, medicine, and fine chemicals with great success. However, there has been no mention of application research in nuclear power plants so far. This paper evaluates the feasibility of ceramic membranes in a primary coolant water environment in terms of filtration materials and fluid compatibility. The researchers tested the chemical stability of the flat ceramic membranes and observed the variation of dissolved elements concentration with time, mass and temperature. The dissolved elements are mostly Al, Si, Mg, and Ti, according to the results. The leachable Si element is the most abundant, followed by Al and Mg, with a very low eluted Ti percentage. With increasing duration, mass, and temperature, the dissolved elements of the flat ceramic membrane in the simulated primary coolant water environment rise. With time, the rate of dissolved element release diminishes. The dissolving rate tends to a constant value until a particular concentration (about 10 mg/L in this experiment) is reached. The existing flat ceramic membrane is not suited for the primary coolant water environment of PWR nuclear power plants due to the high dissolving rate of each element.