Several methods of interval mapping of QTLs underlying endosperm traits based on random hybridization designs and the triploid genetic model are proposed. The basic idea is: plants (or lines) from a population with known marker genotype information are randomly hybridized to generate a population of hybrid lines for endosperm QTL mapping; a mixture of seeds of each hybrid line is measured for the en- dosperm trait to get the mean of the line; then en- dosperm QTL mapping and effect estimation is per- formed using the endosperm trait means of hybrid lines and the marker genotype information of parental plants (or lines). The feasibility and efficiency of the methods are examined by computer simulations. Results show that the methods can precisely map endosperm QTLs and unbiasedly and efficiently es- timate the three effects (additive effect, first dominant effect, second dominant effect) of endosperm QTLs. Several methods of interval mapping of QTLs underlying endosperm traits based on random hybridization designs and the triploid genetic models are. The basic idea is: plants (or lines) from a population with known marker genotype information are randomly hybridized to generate a population of hybrid lines for endosperm QTL mapping; a mixture of seeds of each hybrid line is measured for the en- dosperm trait to get the mean of the line; then en- dosperm QTL mapping and effect estimation is per-formed using the endosperm trait means of hybrid lines and the marker genotype information of parental plants (or lines). The feasibility and efficiency of the methods are examined by computer simulations. Results show that the methods can precisely map endosperm QTLs and unbiasedly and efficiently es- timate the three effects (additive effect , first dominant effect, second dominant effect) of endosperm QTLs.