Many people sweat when they are running. It is the normal physiological response. Sometimes you just wipe it. But if you feel uncomfortable, you can take a cloth around your neck, and when sweat flow, you can keep it out conveniently. Or a headband may not be a bad choice. It can stop the sweat down into eyes.
You can choose to buy a piece of hair band that is intended for people when they are doing sports. It is very convenient and there are various kinds both for males and females. You can just put the sports hair band around your head to let the hair be restrained above the band, so that the sweat can not go down along the hair to flow down in your eyes. This is quiet practical and many sports lovers are wearing the hair band. You should choose those hair bands made of air-permeable material in case that the hair band is soaked with sweat making your head uncomfortable.