The present invention provides a V2X communication performance method which is performed by a vehicle-to-X (V2X) terminal in a wireless communication system, and which is based on a relatively short transmission time interval (S-TTI) compared to a legacy transmission time interval (L-TTI), whereby a channel busy ratio (CBR) or a channel occupancy ratio (CR) for the S-TTI-based V2X communication is measured, and the S-TTI-based V2X communication is performed based on the measured CBR or CR, wherein the S-TTI has a variable length.