To investigate the variations of physico-chemical factors and microbial population, in ten stations at water region of coastal area of Chagwi-Do, Nutritive salts, water temperature, transparency, suspended solid, salinity, COD, DO, pH, heterotrophic bacteria, were analysed three times in September, November in 2004 and February in 2005. Heterotrophic bacteria in surface water was $3.5 imes10^1sim1.16 imes10^3;cfu;mL^{-1}$, $0.4 imes10^1sim5.6 imes10^1;cfu;mL^{-1}$, $0.4 imes10^1sim7.8 imes10^1$ and bottom water counted $4.5 imes10^1sim1.0 imes10^3;cfu;mL^{-1}$, $1.2 imes10^1sim1.5 imes10^2;cfu;mL^{-1}$, $0.4 imes10^1sim4.4 imes10^1;cfu;mL^{-1}$ in September, November 2004 and February 2005, respectively. The dominant species isolated from the coastal area of Chagwi-Do were identified to be Vibrio spp., Pseudoalteromonas spp. Psuedomonas spp, Bacillus spp., Alteromonas spp., Aeromonas spp., Psychrobacter spp., and Flavobacterium spp.