This paper proposes a tiltable multiple-effect solar distiller and presents a numerical analysis on its performance. The distiller consists of a glass cover, a number of parallel plates, and seawater-soaked wicks placed in contact with the plates. The wick of the glass cover is designed to be black color to increase the solar energy absorption. A 2-dimensional numerical model of heat and mass transfer was developed to analyze the distiller's optimal operating and design conditions, and a numerical analysis was conducted in each of the four seasons at N30 degrees and E127 degrees. The results show that the TMED can produce the fresh water of 16.6 kg/m(2) by optimal operation and the performance ratio is 1.44, which is 2.8 times more than that of a basin-type still. The wind reduced the productivity of the distiller due to heat loss from the glass. Although the productivity increased with decrease of inclination angle of the distiller, the optimum value was 40-50 degrees considering deformation of plate and contamination of fresh water. Feeding the same flowrate of 6 ccm to all effects was recommended for convenient and reliable operation. The optimal number of effects was 11 based on annual productivity and manufacturing cost.