Hydrodynamic characteristics of a near-wall circular cylinder oscillating in direction perpendicular to steady current are experimentally investigated at a Reynolds number of 2× 105. Forces in both in-line and cross-flow are measured by the three-dimensional force transducers. The effects of gap ratio, oscillating frequency and amplitude on the hydrodynamic charactersistic of the cylinder are studied. Experimental results indicate that 1) mean drag reduces rapidly when the gap ratio decreases from 0.7 to 0.3; 2) for an oscillating cylinder, the critical gap ratio of vortex shedding suppression is smaller than that for a still cylinder; 3) the existence of near-wall influences the energy transfer between the structure and fluid significantly, which means that hydrodynamic coefficient based on free-wall cylinder may not be suitble for predicting vortex induced vibration of pipelines; 4) for an oscillating cylinder, added mass is not a constant except for in a certain range of oscillating frequency, and the absolute value increases with the decrease of gap ratio in low frequency range; 5) mean drag coefficient, oscillating drag coefficient and oscillating lift coefficient all increase with oscillating amplitude increasing.