Abstract: Vacuum sintering and sintering in hydrogen atmosphere of warm-compacted green compacts has been studied.During compacting of iron powders, the temperature of iron powders was 110℃, the temperature of the die tool was 80~100℃. During sintering, the green compacts were loaded at the room temperature, the heating up rate was 2. 5℃/min.The sintering temperatures were 1100, 1150 and 1250℃ respectively. Experimental results show that sintering densities of all compacts decrease after sintering at all given temperature for 1h in vacuum or in hydrogen atmosphere. Variations of weight and volume of the compacts after sintering and the final sintered densities through pre-sintering were measured,finding that high temperature sintering at 1250℃ with pre-sintering can effectively enhance the final sintering densities of the green compacts. The present study indicates that the density value of sintered iron is consequent results of the combination effect of warm-compacting and sintering. One of two processing may lead to the variation in the final density of the compacts. And although warm compaction may increase the density of the green compact, the sintering behavior of warm-compacted green compacts should be taken into account for optimizing the temperature and specification of warm-compaction.