Soil suitability evaluation and rational utilization modes were studied. IIainan Island was divided into 4094 grids which were regarded as the soil resources units to be evaluated. Of the 4094 grids, 570 were chosen as typical ones (trained samples) and further divided into 8 groups representing the successful soil utilization modes on the Island (i.e. paddy field, upland field, forestry 1, forestry 2, tropical cropland 1,tropical cropland 2, pasture and others). 11 variables (i.e. evaluation items including altitude, Soil type humus reserves, solum thicl;ness and slope, et.c.) were selected and rcasonablely dibitized for ca,lcula.tion. Aftsr stepwise multfiple diseriminant analysis, all 11 varubles were proved effective, while 8 initial groups were further a.djust.ed to the optimum. The adjusted groups constituted soil suitability evaluation criteria. Based on discriminant funnetions, other 3464 grids were allocated into corresponding optimum groups. A rational soil utiLization map of the Islaud was output automatically by computor. In addition, a map of sail utilization regionalizatibn wets finished. On the m.ap, 7 utilizalion regions were delimitated. It is concluded that the Island possesses great. potentiality of developing tropical crops, agriculture and forestry.