A method of sharing radio resources for licensed assisted access (LAA) in unlicensed spectrum and related devices using the same are provided. In one of the exemplary embodiments, the disclosure is directed to a method used by a user equipment for sharing radio resources for LAA in an unlicensed spectrum. The method would include not limited to transmitting or receiving, through a LTE protocol, a first data in a licensed spectrum; transmitting or receiving, through the LTE protocol, a first control signal in the licensed spectrum for receiving a second data in an unlicensed spectrum; transmitting or receiving, through a LTE-unlicensed (LTE-U) protocol, the second data in the unlicensed spectrum within a first time window without transmitting a random access (RA) request; and stopping transmitting, through a Wi-Fi protocol, any RA request as long as the first time window has not expired.