Abstract: Accurate calculation of natural frequencies and sensitivity analysis of parameters are critical for designing suction bucket offshore wind turbine (OWT) systems. We develop an analytical model to enable accurate and efficient parameter sensitivity analysis. It incorporates the tower’s variable cross-section, hydrodynamic effects, flange bolt mass, and interaction between the suction bucket and soil. The model is formulated by the method of reverberation-ray matrix. A closed-form characteristic equation for natural frequencies is derived, yielding precise analytical solutions. A comprehensive sensitivity analysis of the fundamental frequency is subsequently conducted. The main findings are: (1) The fundamental frequency decreases with reduced soil modulus or increased scour depth. Their coupling effect lowers the safe scour depth threshold to 0.476 times the burial depth. (2) As a rigid foundation structure, the system shows the sensitivity of the fundamental frequency to sea depth, suction bucket diameter, and thickness. However, this sensitivity is relatively weak and can be regarded as a secondary factor. (3) The parameters most influencing the fundamental frequency are ranked by sensitivity as follows: tower height > tower diameter > suction bucket height > scour > elastic modulus at the connection section > tower thickness > seabed soil degradation.