Drought is one of the major abiotic stresses limiting rice (Oryza sativa L.) production. Quantitative trait loci (QTLs) for drought tolerance (DT) at the reproductive stage were identified with two sets of reciprocal introgression lines derived from Lemont × Teqing. In total, 29 and 23 QTLs were identified in the Teqing and Lemont backgrounds, respectively, during the reproductive stage under drought and irrigated conditions for spikelet number per panicle, seed fertility, filled grain weight per panicle, plant height, and grain yield per plant. Most of these QTLs showed obvious differential expressions in response to drought stress. Another 21 QTLs were detected by the ratio of trait values under drought stress relative to the normal irrigation conditions in the two backgrounds. For 28 DT QTLs, the Teqing alleles at 23 loci had increased trait values and could improve DT under drought stress. Only five (17.9%) DT QTLs (QSnp1b, QSnp3a, QSnp11, QSf8, and QGyp2a) were consistently detected in the two backgrounds, clearly suggesting overwhelming genetic background effects on QTL detection for DT. Seven of the DT QTL regions identified were found to share the same genomic regions with previously reported DT-related genes. Introgressing or pyramiding of favourable alleles from Teqing at the validated QTLs (QSnp3a, QSnp11 and QGyp2a) into Lemont background may improve DT level of Lemont.