Abstract Sensitivity is of great importance for piezoelectric resonance mass sensors in the fields of material and particle analyzing. Different from the custom used methods such as geometric dimension reduction and configuration modification, a new sensitivity improving method was proposed by simultaneously modifying both the surface profile and the cross-section type of the cantilever to optimize its stiffness and mass distribution. Knowing the effects of the structural parameters on the resonance frequency, a novel piezoelectric resonant mass sensor was designed and fabricated by introducing the grooved trapezoidal cantilever with variable cross-section as the key elastic element. Through the cantilever vibration analysis by the finite element method, the sensitivity analyzing model for the grooved trapezoidal cantilever mass sensor was established, with which, the influence of the groove and profile parameters on the sensitivity improvement was systematically analyzed. The experimental and simulated sensitivities of the proposed sensor are 33.7 × 10 3 Hz/g and 38.0 × 10 3 Hz/g respectively, which are nearly 387.8% greater than that of the custom rectangular cantilever sensor of 9.8 × 10 3 Hz/g. More importantly, the proposed sensor also possesses the character of high sensitivity for distributed mass detection, which is 2.92 times that of the rectangular cantilever sensor. Finally, the feasibility and effectiveness of the newly proposed sensitivity improving method was validated.