This paper investigates the effect of a linear adjustment of a search space size in genetic algorithm (CA) on the macroscopic statistical properties of population (such as the average fitness and the variance fitness of population). The equations of motion were derived for one-max problem that expressed the macroscopic statistical properties of population after the adjustment of a search space size. Analysis of a performance of CA that includes a computational cost and a quality of the optimal solution was made for linear and power laws of search space adjustment.