A new analytical method based population dividing is proposed by analysing population clustering. Stochastic distribution equation and growth equation of blocks were deduced. Gene independence was defined to analyse building block hypothesis. A new explanation that decimal-coded genetic algorithms to simulate evolutionary was proposed. A novel genetic algorithm based species selection was proposed and the background on biological of GASS is expounded. Simulation results on a set typical test functions with 100 dimension are presented and the results obtained show that the new approach is a general, effective an d robust method.