To determine the successional level of soil ecosystem, microbial population was examined and environmental factors were measured. Sampling site were evergreen forests area. Among the environmental factors, total organic matter was ranged 11.880(Yesong-Ri, Wando-Gun, Jeoranam-Do)∼66.20㎎/g dried soil(Ggamak Island, Kangjin-Gun, Jeoranam-Do) in surface soil and 4.500(Mok Island, Uljoo-Kun Kyungsangbuk-Do)∼17.000㎎/g dried soi(Ggamak Island, Kangjin-Gun, Jeoranam-Do) in deep soil. Average total organic matter were 23.940 in surface soil and 11.988㎎/g dried soil in 15㎝ depth of soil. Soluble sugar content were measured from 0.045(Maengsun-ri, Wando-Gun, Jeoranam-Do) to 0.172㎎/g dried soil(Mira-ri, Wando-Gun, Jeoranam-Do) and average was 0.103㎎/g dried soil in surface. In 15㎝ depth of soil, it was ranged 0.019 (Maengwun-Ri, Wando-Gun, Jeoranam-Do)∼10.131㎎/g dried soil and average was 0.065㎎/g dried soil. On the basis of these experimental data, S/O value, the ratio of soluble sugar against total organic matter, in surface soil was ranged 0.002(Ggamak Island, Kangjin-Gun, Jeoranam-Do)∼0.095 (Jindo-Gun. Jeoranam-Do), and average was 0.005. And also it was ranged 0.001 (Maengsun-Ri, Wando-Gun. Jeoranam-Do) in lower depth of soil and average was 0.006. And all of S/O value were higher than 0.00371 in Mt. Palwang, 0.0018 in Mt. Weolchul and 0.0005 in Mt. Jukyeop. However, they were much lower than 0.0252 in Mt. Jiri and 0.16 in Mt. Kyebang. From the above result, it can be concluded that S/O value, the ratio of soluble sugar against total organic matter, in soil, was useful parameters for soil environment of climax forest in ecosystem.