Both Han China, as well as the Roman civilization, allowed ownership of slaves and supported the idea of forcing them to work. However, the difference between the two is that China did not greatly rely on their slaves, where as it was a critical and indispensable part of the Roman economy.
In the Roman Empire, during the second century B.C.E., there was a relatively large amount of wars. Being that Rome won a majority of those wars, this non-coincidentally led to the capture of many prisoners. These prisoners, in turn, became slaves. Because of the surplus in the amount of slaves, they were cheap and affordable for many households and businesses. Manufactures and landowners also found it easier to convince these slaves to work harder and longer compared to other hired help. Because these slaves were doing a majority of the physical labor, as well as other things, they became an integral part of the Roman economy. It is also for this same reason that slaves in Rome were treated so poorly, or at least worse than their counterparts in China. The Romans knew that their economy would collapse if, for whatever reason, they no longer had slaves. Because of this, they tried to guarantee that nothing of the sort would ever happen.
One of the best ways to keep control of a people is through fear. If they are terrified that they will be beaten or executed, they are less likely to try to do things considered unacceptable. Fearing revolts that would lose the security of their economy, the Romans treated their slaves badly in order to implant that fear into their minds.
In contrast to the Roman Empire, the Han Dynasty of China was much less dependent on slave labor as a backbone of their economy. One proof of this is the fact that the Qin Dynasty tried to do away with slavery. Had it been an important part of society, they would not have done so. Another reason slaves were less crucial to the Han is because in China, the slaves were generally used to do domestic tasks, such as cooking, cleaning, or going shopping. This is very different from the Romans, in which they often had their slaves do important jobs, such as a lawyer or doctor. The treatment of slaves was also less harsh in China than in Rome. In the Han, a slave had a written contract specifying and limiting exactly what tasks he or she could be forced to do. If asked to do a task not on this list, it was not unheard of for a slave to refuse and not be punished for it. This would rarely happen in Rome, as such a recusant slave would be in fear of severe beatings.
Bulliet, Richard W. Earth and Its Peoples: Complete. Houghton Mifflin College Division, 2004.