Resonant converters are widely used in high voltage applications thanks to the soft switching technologies. The high frequency and high voltage (HFHV) transformer is the most complicated and important part to boost the voltage by tens or hundreds of times, and the parasitic capacitance of the transformers is critical to the performances of resonant converters. To reduce the parasitic capacitance, the multi-section winding technique is usually employed in HFHV transformers. However, the parasitic capacitance values calculated by the classical methods are not consistent with the experimental results of HFHV transformers, and they are usually designed and optimized with low efficiency. This paper proposes a new analytic method for calculating the parasitic capacitance of HFHV transformers of multi-section windings, which is verified with good accuracy by experimental results.