The result of concrete dry ice cleaning test with KBQX-30DG，which is a single tube dry ice cleaning machine，shows cleaning effect is good，but can make pore on the concrete surface. Based on the orthogonal experiment design method，study the four factors of dry ice flow，cleaning distance，cleaning time and injection angle in the process of dry ice cleaning how to affect the surface porosity growth. The range analysis results show that the most important factor to the surface porosity growth is dry ice flow. With the dry ice flow increase，the surface porosity growth increased，and the surface porosity growth will leap when the dry ice flow is greater than 1.54 kg/min；the injection angle has obvious influence on the surface porosity growth，when injection angle is in the scope of 55°~60°and 85°~90°，and the amount of pore is more than these in the scope of 65°~70°and 75°~80°；the influence on the surface porosity growth of cleaning distance and cleaning time is not obvious. By linear regression analysis and AHP we can obtain the weights on the surface porosity growth of four factors’ through which we can get the primary and secondary order of each factor，and the result is consistent with the range analysis.