This paper made a systematic researches on the determination on the level of soil and water loss in leveling area of development and construction (not being adopted the measurement of soil and water conservation). The determination of criteria of the level of erosion in urbanized development area is different from that of traditional soil and water loss in countryside. Through a large scale of field investigations and experiments, we analyzed the erosion modulus in leveling area correspondent with the characteristics of development area (including the soil type, this paper mainly research the area making up of red granite soil), and the results showed that the soil erosion modulus in serious level of leveling area is average 20 000~60 000 t/(k㎡.a),some erosion modulus may be up to more than 100 000 t/(k㎡.a). The paper reports the results of systematic research on the determination on the level of erosion and erosion modulus in construction development area first time. These results have provided the planning of soil and water conservation in Shenzhen City with scientific basic data, and it will be helpful for the work of soil and water conservation in other urbanized area.