The price indexes for city used house belong to the real estate price indexes. They will reflect the fluctuation of the used house price, forecast the direction of the up-and-down price, induct the citizens to make deal in reason and support the government to make policy with the price information. For complex bargaining of the used house in city, it is difficult to make the price index for city used house exactly. There will be a lot of difficulties for making the indexes. This paper expands and analyzes the difficulties in confirming the representative district, choosing the fixed time and selecting the case. Then, this paper analyzes the regional adjusting factors from the qualitative and quantitative factors in detail. It works out the influencing degree of regional factors with Delphi. Meanwhile, it calculates the correctional coefficient on the basis of qualitative facet and introduces the method of making price index for city used house on the basis of quantitative facet.