The paper analyses the commodity house price, land price, building and equipping cost and developer’s profit around “8.31”, and compares the ratio of land price to house price. We find that the ratio of land price to house price is stable. We analyses the factors that affect house price based on our analysis. We use examples to show that land price, building and equipping cost, developers’ expected profit is the main factors that affect house price. We analysis the ratio of land price to house price around “8.31” based on the difference of building cycle, we find that the ratio of land price to house price reduces with the average building cycle increased (This is innovation of this paper), the ratio is about 10% or 20%. Then we use gray relation degree to analysis the factors affecting the house price, show that per income, population and per inhabitant condition are the main factors affecting land price of ShenZhen. Analyzed land price building and constructing cost, we find out expected profit of developer is the main cost factors affecting real estate price through the case.