A method for enhancing the mobility of a working fluid in a liquid/gas phase heat dissipating device improves the mobility of the working fluid therein, and further enhancing the heat dissipation capability of the heat dissipating device. The present invention coats a layer on the surface of a capillary structure inside the heat dissipating device to increase the material property on the surface and the coupling force between the working fluid and the capillary structure and decrease the contact angle between the working fluid and the capillary structure, and thus the working fluid has a higher mobility to solve the problem of the high heat flux density of the liquid/gas heat dissipating device and improve the heat dissipation effect. The present invention not only applies to the heat generating electronic components within a limited space, but also applies to other electronic components that require a constant temperature.