Parasitic parameters, such as leakage inductance and parasitic capacitance, are often used as indicators for optimizing planar transformers. However, simply changing the interlayer winding arrangement only reduces leakage inductance while inversely increasing parasitic capacitance, complicating the optimal transformer design. This paper investigates an interlaced winding structure within layers under a high coupling strategy, achieving simultaneous reductions in leakage inductance and parasitic capacitance. This paper also improves the leakage inductance calculation for interlaced structures within layers, addressing the issue of applying the MMF algorithm. Furthermore, this paper analyzes the energy loss distribution and other parameters of the interleaved structure through model simulation of a four-layer plate transformer, comparing the differences in parasitic parameters across various winding structures. The results demonstrate that the proposed winding structure exhibits lower parasitic parameters and reduced AC resistance. Finally, a planar transformer is fabricated to verify the performance of the proposed structure.