Abstract: A double haploid(DH) population consisting 123 lines, derived from an indica variety IR64 and a Japonica variety Azucena, were used in a hydroponic experiment with K sufficient (140mg/kg) and deficient (5mg/kg) treatments. The parameters, including plant height (PH). tiller number (TN). shoot dry weight (SDW). root dry weight (RDW) and K content in plant (KC) were measured after culture for 4 weeks. K uptake (KUP) and K use efficiency (KUE) defined as biomass production per mg of absorbed K were calculated according to the measurements. Oe hundred and seventy five molecular markers mapped on all 12 chromosomes were used for analysis of QTLs for the parameters. QTLs underlying tolerance for K deficiency was defined as the gTLs detected only under K deficient condition (K-deficiency induced QTLs). The results indicated that the variation in PH was mainly controlled by sd-1 locus under both K sufficient and deficient conditions. but 4 K-deficitncy induced QTLs were detected.Three K-defficiency induced QTLs conditioning TN were observed. Under K sufficient condition. sd - 1 locus also influenced other parameters. but not under K deficient condition. Three identical QTLs under K deficient condition for SDW and RDW were detected, one of them, was also found to affect KC, KUP and KUE and the other two also affected KUP. The mean comparisons for the parameters betWeen tWo genotypic classes at the marker locl linked to the QTLs indicated that the genotypic class of IR64 is superior to that of Azucena for all of the parameters, except KUE. The results may be helpful for us to understand the genetic background on the tolerance for Kdeficiency in rice.