By analyzing 2.93fb−1 of data taken at the ψ(3770) resonance peak with the BESIII detector, we measure the branching fractions for the hadronic decays D+→KS0KS0K+, D+→KS0KS0π+, D0→KS0KS0 and D0→KS0KS0KS0. They are determined to be B(D+→KS0KS0K+)=(2.54±0.05stat.±0.12sys.)×10−3, B(D+→KS0KS0π+)=(2.70±0.05stat.±0.12sys.)×10−3, B(D0→KS0KS0)=(1.67±0.11stat.±0.11sys.)×10−4 and B(D0→KS0KS0KS0)=(7.21±0.33stat.±0.44sys.)×10−4, where the second one is measured for the first time and the others are measured with significantly improved precision over the previous measurements.