The smell coming from the drain in your basement floor could be sewer gas. The gas is usually blocked from entering your home by water in a trap. If the trap dries out, there won't be a barrier between the sewer the drain empties into and your basement, according to the University of Minnesota.
Pouring a small amount of water into the drain will fill up the barrier portion of the trap and prevent sewer gas from entering your basement. This will stop the smell. If you continue to smell the odor after pouring in water, contact a plumbing professional. She can tell you if something is wrong within the drain itself, like a loose access plug that needs to be refitted.
You should not ignore a smelly drain in your basement floor. Sewer gas contains components that can cause health problems in people exposed to it. In high enough concentrations, it can also explode or catch fire, damaging your home and putting your life at risk, according to Wisconsin Department of Health Services.