In this study, a scheme for measurement equipment based on hollow photonic crystal fiber was proposed to meet the measurement requirement of laser frequency tuning ratio. First, the scheme of the measurement equipment and basic structure of the photonic crystal fiber resonator (PCFR) were designed and the numerical calculation and mechanism analysis of the laser frequency tuning ratio were completed. Second, PCFR was designed and manufactured, and the laser frequency tuning ratio testing setup was constructed. Finally, the frequency tuning ratio of narrow line-width fiber laser and semiconductor laser were tested. The voltage-frequency tuning ratio of the fiber laser is 17.6 MHz/V, which is in accordance with the factory indicators; moreover, the fiber laser''s tuning ratio is consistent at the tuning range. The tuning ratio of semiconductor laser in tuning range is non-consistent, which is susceptible to environmental influences. The average current-frequency tuning ratio of the semiconductor laser is 30.9 MHz/mA. This study demonstrates that the accuracy of the proposed testing setup is much higher than that of the commercial wavelength meter, and it also displays good long-term stability. Furthermore, PCFR has technical advantages, such as high frequency measurement accuracy and small temperature drift, as a frequency reference for frequency tuning ratio detection.