Pressure fluctuations in intake manifold of Internal Combustion Engine introduce a pulsating boundary condition to the centrifugal compressor. In this study, the performance of centrifugal compressor exposed to pulsating backpressure is experimentally investigated. Unsteady performance and surge characteristic of the compressor at different pulsating conditions are analyzed. Results show that instantaneous performance of the compressor forms a hysteresis loop encapsulating steady performance. A correlation of compressor unsteadiness with pulse frequency, magnitude, and local slope of the characteristic curve is obtained based on measurements. Cycle-average performance of the compressor is notably lower than that at constant conditions. Specifically, the averaged peak efficiency at pulsating condition drops 3%~7%. Fast Fourier Transformation method is applied to study surge characteristics at pulsating conditions. Results manifest that compressor surge is postponed remarkably by pulsating backpressure at all conditions. As the compressor approaches to small mass flow rate, flow fluctuations decay quickly and then increase dramatically when the surge happens, forming the variation with 'V-shape' for frequency domains. This phenomenon is resulted from the influence of the slope of characteristic curve on the filling-empty and compressor stability. Smaller slope produces less filling-empty and hence smaller size of the loop, but reduces the stability of compressing system and initiates surge.