The invention discloses a low dielectric constant glass plate and a preparation method thereof. The glass batch of the glass plate comprises the following components in percentage by mass: 55-75 % of SiO2, 5-15 % of Al2O3, 0-10 % of MgO, 1-15 % of K2O, 0-10 % of Na2O, 0-5 % of Li2O, 0-10 % of CaO, 0-10 % of B2O3, 5-20 % of ZrO2 and 0.5-2 % of clarifier, wherein the total mass percentage is 100 %; the clarifier is a mixture of SnO2 and CeO2, wherein the CeO2 accounts for 20-50 % of the total quantity of the clarifier. The low dielectric constant glass plate disclosed by the invention can be directly used as a circuit board, obtains higher heat stability and is suitable for working in electronic components under a severe environment for a long time; through the adding of a zirconium element, the dielectric constant can be adjusted, so that dielectric constant and dielectric loss at a lower level are achieved; through the integral formula composition of the glass and the adoption of a composite clarifier, the glass plate obtains better clarifying quality; moreover, the characteristics of the low dielectric constant glass plate disclosed by the invention are suitable for large-scale production in a floating or overflow down draw process; and the manufacturing cost is reduced.