This study was aimed to use the method of modulation transfer function (MTF) to compare image quality among three different Olympus medical rigid cystoscopes in an in vitro model.During the experimental processes, we firstly used three different types of cystoscopes (i.e. OLYMPUS cystourethroscopy with FOV of 12°, OLYMPUS Germany A22003A and OLYMPUS A2013A) to collect raster images at different brightness with industrial camera and computer from the resolution target which is with different spatial frequency, and then we processed the collected images using MALAB software with the optical transfer function MTF to obtain the values of MTF at different brightness and different spatial frequency.We then did data mathematical statistics and compared imaging quality.The statistical data showed that all three MTF values were smaller than 1.MTF values with the spatial frequency gradually increasing would decrease approaching 0 at the same brightness.When the brightness enhanced in the same process at the same spatial frequency, MTF values showed a slowly increasing trend.The three endoscopes' MTF values were completely different. In some cases the MTF values had a large difference, and the maximum difference could reach 0.7. Conclusion can be derived from analysis of experimental data that three Olympus medical rigid cystoscopes have completely different imaging quality abilities. The No.3 endoscope OLYMPUS A2013A has low resolution but high contrast. The No.1 endoscope OLYMPUS cystourethroscopy with FOV of 12°, on the contrary, had high resolution and lower contrast. The No.2 endoscope OLYMPUS Germany A22003A had high contrast and high resolution, and its image quality was the best.