Abstract: In order to minimize osmotic and toxic damage to oocytes during cryopreservation， microfluidic device has been applied to the continuous loading and unloading of cryoprotective agents （CPAs）. In this study，a micromixer model based on S\|shaped channel was established for the process of CPA loading， the effects of channel geometrical and operating parameters on the fluid mixing performance were investigated， and theoretical optimization was carried out for them. Results showed that the fluid mixing performance increased with the increase of height and decrease of width of the mixed channel. When the Reynolds number was in the range of 004～112， the two\|fluid was mixed only by the molecular diffusion at a laminar flow state， and with the increase of Reynolds number， the diffusion time decreased and the mixing length increased; the secondary flow from curve channel played an important role in the fluid mixing， significantly improved the mixing efficiency. Meanwhile， the curve channel will not increase local resistance of fluid flows. These conclusions have the certain reference values for the optimal design of the micro mixer and later oocyte cryopreservation experiment.

Key words: occyte, cryopreservation, micromixer