Recently I have made a power supply which gives dc voltage between 1.2 ~ 30 But when I use my multimeter I can measure AC voltage too is that normal ? Shouldn't it be zero ?
Since your multimeter reads significantly differently from non-zero with a battery input, your power supply is probably okay. That's a bit of a strange voltage reading- maybe 1/2 wave rectified with DC coupling.
You van try a capacitor in series with the input of the meter- maybe 10uF.