The Ser-Su-Ken Lake is a landslide-dammed lake caused by the Chi-Chi Earthquake. The morphological and area change of the lake was monitored by satellite remote sensing. The contribution degree of lake water physic-chemical variables to the simple ratio water reflectance index (SRWRI), i.e. IR/R, calculated from satellite digital data, was compared using grey relational analysis. The lake morphology changed significantly and the area increased more than ten fold within ten months after the quake. The grey relational analysis shows that the individual components of organic materials, inorganic materials, or Chl a content, an algae growth indicator, made slightly different contributions to the WBRI at five sampling sites. CTSI, pH, Temp, and DO had the greatest influence on the SRWRI of Ser-Su-Ken Lake for one-and-a-half years after the Chi-Chi Earthquake; inorganic matter played a much larger role than organic matter did; and BOD, PO4-, NH4+, NO3-, and NO2- contributed the least of all physic-chemical variables. This is the first report to use a grey relational analysis to solve an important question in limnology unresolved by traditional mathematics and statistics.