Yes, you will need to pay Stamp Duty Land Tax on a Buy To Let property if it is your second property and not your main residence.
The amount you will have to pay depends on the purchase price. See details below:
Less than £125,000 – 3%
£125,001 – £250,000 – 5%
£250,001 – £925,000 – 8%
£925,001 – £1.5 million – 13%
£1.5 million and above – 15%
Information correct as of April 2017 – Source:www.gov.uk/stamp-duty-land-tax/residential-property-rates