Disclosed is a method of joint optimization of channel selection and frame scheduling for coexistence of LTE and WLAN in an unlicensed band, the method being performed by a baseband unit (BBU) pool and the method includes: selecting a component carrier (CC) having a highest idle probability by considering an idle probability of the CC for the unlicensed band; determining the number NI of idle subframes in the selected CC by considering a residence time in a WLAN system queue; and allocating a resource block (RB) to an LTE user terminal in a cell based on the number of selected CCs and the number of idle subframes and which appropriately selects a resource in a frequency domain and a time domain in LTE to acquire high throughput and fairness in the LTE and the WLAN in the unlicensed band.