To accurately detect the H2 concentration in liquid phase, a H2 sensor was fabricated using palladium, silica superhydrophobic sol and tilted fiber grating. First, to respond the hydrogen concentration, a layer of dense Pd film was coated on the surface of the tilted fiber grating by using the magnetron sputtering method. Then, a layer of silicon oxide superhydrophobic film was coated on the surface of the Pd film by using a dip coater, which was used to prevent water molecules from entering into the palladium film, causing the palladium film to detach from the surface of the optical fiber, thereby enhancing the stability of the sensor in the liquid phase environment. The effect of the thickness of the Pd film on the hydrogen-sensitive response characteristics of the sensor was experimentally studied, and H2 concentration in the liquid phase was detected using the sensor. The study shows that the sensor can accurately respond to the change of the H2 concentration in liquid phase, and when the thickness of the Pd film is 120 nm, the sensitivity reached -15.29 pm/% and the maximum relative error is 8.67%.