无源谐振腔的有效谐振频率（被测得谐振频率）偏移作为参考的基模谐振频率的效应是谐振腔中存在的高阶横模所引起的。由光探测器光接收孔径的有限性或表面的不均匀性而导致各阶横模的空间不正交性，是引起谐振频率偏移效应的主要原因。对此作了详细研究，并对计算结果进行了讨论，总结出谐振频率偏移与谐振腔各参量的相互关系，从而提出减小这种效应的有效措施。 The effect of offsetting the effective resonant frequency of the passive cavity (measured resonant frequency) as the reference fundamental resonant frequency is due to the presence of higher order transverse modes in the resonant cavity. Due to the limited aperture of photodetector or the nonuniformity of the surface, the spatial orthogonality of transverse modes is the main cause of the resonance frequency shift. In this paper, a detailed study is carried out, and the calculation results are discussed. The relationship between the resonance frequency offset and the parameters of the resonator is summarized, and an effective measure to reduce this effect is proposed.