The large scaled field test by prefabricated vertical drains was performed to evaluate the superiority of vertical discharge capacity for drain materials through compare and analyze the time-settlement behavior with drain spacing and the compression index and consolidation coefficient obtained by laboratory experiments and field monitoring system 1. The relation of measurement settlement(S_m) versus design settlement(S_t) and measurement consolidation ratio( U_m) versus design consolidation ratio(U_t) were shown S_m=(1.0~l.1) S_t, U_m=(1.13~l.17) U_t, at 1.0m drain spacing and S_m=(0.7~0.8) S_t, U_m=(0.92~0.99) U_t at 1.5m drain spacing, respectively. 2. The relation of field compression index(C_cfield) and virgin compression index(V_cclab) was shown C_cfield=(1.0~1.2) V_cclab, But it was nearly same value when considered the error with determination method of virgin compression index and prediction method of total settlement. 3. field consolidation coefficient was larger than laboratory consolidation coefficient, and the consolidation coefficient ratio(C_h/C_v ) were C_h=(2.4~3.0)C_v. C_h=(3.5~4.3)C_v) at 1.0m and 1.5m drain spacing and increased with increasing of drain spacingngasing of drain spacingng spacingng