Dust-acoustic solitons in dusty plasmas with two-temperature isothermal ions are investigated by considering an effect of self-consistent dust-charge variation. Employing the reductive perturbation technique we derived dust-acoustic solitons. It is found that both rarefactive and compressive solitons exist and the approximate similarity law which holds in dust-charge-fluctuation plasma system with one-temperature ion does not survive in the present studied dusty plasma with two-temperature isothermal ions.