Abstract: Using Cl₂/H₂ as etching etchants,the surface damage of the InP/InGaAsP material in ICP etching system was investigated.By measuring the changes of photoluminescence（PL）intensity from a specially designed InP/InGaAsP multi-quantum well（MQW）in both exposed and protected regions, and utilizing a Gaussian Depth Distribution model,the extent of damage was quantitatively analyzed.The influences of pressure,ICP power,RF power and Cl₂/H₂ mixing ratio of ICP system on the surface damage extent were revealed.Based on these results,a set of optimized low damage etching parameters with a less than 16nm damage-depth was finally obtained.