Why I'm getting amplification even without template in PCR reaction?

If your PCR conditions were optimal and there was no DNA template in the reaction mixture, then amplification should not occur. If for some reason DNA amplification does happen, it is most likely due to the presence of contaminates in your PCR components (e.g. reagents and equipment). Make sure you take all the necessary precautions to avoid any contamination (e.g. using fresh pipette tips, fresh primer stocks, etc.)