The aim of this study was to compare four different mating strategies in a dairy cattle population to study the effects of inbreeding coefficient on genetic and phenotypic trends and inbreedingdepression in traits such as milk production with moderate heritability with using simulation. For this purpose, four mating strategies and three methods of estimating inbreeding were examined. In the first strategy, selection and mating in the simulated population was done randomly. The second strategy was an optimal mating to reduce inbreeding and increase genetic gain. For this purpose, individuals with the highest breeding value were selected and mated based on the lowest amount of inbreeding. In the third strategy, random selection and mating were based on minimize inbreeding without considering genetic gain. In the fourth strategy, individuals were mixed based on the highest breeding value (positive assortative). Also, to calculate inbreeding in the simulated population, three methods of estimating pedigree inbreeding (F PED ), genomic relation matrix (F GRM ) and base on run of homozygosity (F ROH ) with a minimum length of 25 were used. simulation and mating strategies in ten generations were performed QMSim and 1101 softwares was used to estimate inbreeding. Comparing the three methods of estimating inbreeding (F PED , F GRM and F ROH ), we concluded that the inbreeding estimate based on ROH 25 provided a closer estimate of pedigree inbreeding and a high correlation with pedigree inbreeding and relationship matrix inbreeding. Therefore, due to the problems in pedigree data and also not being dependent on allelic frequency, estimating inbreeding in populations based on this method can be more desirable. The results also showed that if the goal in a breeding program is progress despite the limitation in the rate of increase in inbreeding gain and also the least inbreeding deprission, the optimal mating strategy is more desirable. Key Words: Inbreeding, Mating strategies, Inbreeding depression, Dairy cow, Simulation