Based on the interferences between core modes and cladding modes in photonic crystal fiber (PCF), a novel temperature sensor is presented and experimentally demonstrated. The peak wavelength of the interference spectrum linearly increased with an increase in temperature. A measurement sensitivity of 10.38 pm/°C was experimentally achieved for temperatures ranging from 30°C to 100°C. Experimental results also indicate that the curvature and transverse load do not have a distinguishable influence on the transmission spectrum of the proposed fiber sensor, which ensures its applicability for practical applications.