Pre-welding cleaning process is of great importance for honeycomb sandwich structure to gain a satisfactory brazed joint. Due to the poor stiffness in plane direction of honeycomb core, the more effective cleaning method for honeycomb is non-contact cleaning, including laser cleaning and ion bombardment cleaning. The work aims to study the effects of laser cleaning and ion bombardment cleaning methods on brazing property of GH4099 honeycomb sandwich structure, and optimize the pre-welding cleaning process of honeycomb sandwich structure.